## Course description

- This course covers comprehensively O Level syllabus that are related to Work Energy Power
- The average video duration is less than 3 mins so you will not get bored with the course
- You will learn by watching videos that answers questions with increasing difficulty
- Short helpful notes are also provided
- Practice questions are also provided

### What are the requirements?

- You can start with no or basic knowledge of work energy power

### What am I going to get from this course?

- By the end of this course you will be able to answer simple to difficult questions on this topic easily
- You get to learn at your own pace and watch the videos repeatedly
- Great for students who need an all in one place to rapidly remember what they have learnt
- Students will worry less about losing their paper notes as they can get their information here
- show understanding that kinetic energy, potential energy (chemical, gravitational, elastic), light energy, thermal energy, electrical energy and nuclear energy are examples of different forms of energy
- state the principle of the conservation of energy and apply the principle to new situations or to solve related problems
- calculate the efficiency of an energy conversion using the formula efficiency = energy converted to useful output / total energy input
- state that kinetic energy Ek = ½ mv2 and gravitational potential energy Ep = mgh (for potential energy changes near the Earth’s surface
- apply the relationships for kinetic energy and potential energy to new situations or to solve related problems
- recall and apply the relationship work done = force × distance moved in the direction of the force to new situations or to solve related problems
- recall and apply the relationship power = work done / time taken to new situations or to solve related problems

### What is the target audience?

- This course is suitable for the Singapore Cambridge GCE O level students, relevant to IGCSE students and Singapore's Integrated program students.

Math Arena

The instructor is from Math Arena.The instructor is absolutely passionate about teaching and you'll find the lessons engaging and ultimately rewarding.

## Course Curriculum

WORK DONE BY A FORCE

08:48

A box is being pushed horizontally on a smooth surface by a 10 N force for 6m [WEP1] Q3

A box of mass 2 kg is being pushed horizontally on a smooth surface by a 10 N force for 6m [WEP1] Q4

A box of mass 2 kg is being pushed horizontally on a rough surface by a 10 N force for 6m [WEP1] Q5

A box of mass 2 kg is being pushed horizontally on a smooth surface by a 10 N force for 6m (by the weight of the box) [WEP1] Q6

A box of 2kg is being pushed horizontally on a smooth surface by a 10 N force for 60 cm [WEP1] Q7

KINETIC ENERGY

11:31

A box of mass 2 kg is moving at a constant speed [WEP1] Q8

A box of mass 500g is moving at a constant speed of 72 km/h [WEP1] Q9

A box of mass 2 kg increases its speed from 3 m/s to 7 m/s [WEP1] Q10

A box of mass 2 kg is lifted vertically upwards by 3m. [WEP1] Q11

A box of mass 2 kg is lifted vertically upwards by 3m. [WEP1] Q11 Go Deeper

GRAVITATIONAL POTENTIAL ENERGY

14:36

A box of mass 2 kg is lifted vertically upwards by 3m. (What is the GPE?) [WEP1] Q12

There are 3 paths leading up to a hill [WEP1] Q13

A box of mass 2 kg moves up a ramp from point A to point B. [WEP1] Q14

A box of mass 2 kg moves up a ramp from point A to point B. [WEP1] Q14 Go deeper

A pendulum bob pivots at a point P. [WEP1] Q15

Three different stones are lifted from ground level (Different Planets) [WEP1] Q16

WORK DONE AND KINETIC ENERGY

17:46

A box is being pushed horizontally on a smooth surface by a 10 N force for 6 m. [WEP1] Q17

A 1.2 kg box is being pushed horizontally on a smooth surface by a 10 N force for 6 m. [WEP1] Q18

A 6 kg box is being pushed horizontally on a smooth surface by a 10 N force for 6 m. [WEP1] Q19

A 6 kg box is being pushed horizontally on a rough surface by a 10N force [WEP1] Q20

A 6 kg box is being pushed horizontally on a rough surface by a 10N force [WEP1] Q20 Go deeper

A 6 kg box is being pushed horizontally on a surface by a 10N force for 6m [WEP1] Q21

A 6 kg box is being pulled up a ramp by a force F at a constant speed (involves GPE)[WEP1] Q22

WORK DONE, KINETIC ENERGY AND GRAVITATIONAL POTENTIAL ENERGY

29:12

A 6 kg box is being pulled up a ramp by a force F at a constant speed [WEP1] Q22 Vector triangles method

A 6 kg box is being pulled up a ramp by a force F from rest [WEP1] Q23

A box of 6 kg mass is being pulled by a 50N force from an initial speed of 4 m/s [WEP1] Q24

A box on unknown mass is being pulled by a 8 N force (requires trigonometry) [WEP] Q25

A box of 2 kg mass has initial speed of 10 m/s at the foot of the ramp (max ht, requires trigonometry) [WEP1] Q26

A box of mass 2kg has an initial speed of 10 m/s at the foot of the ramp (height h, requires trigonometry) [WEP1] Q27

A box of mass 2 kg slides down from the top of the ramp with an initial speed of 0 m/s [WEP1] Q 28

WORK DONE AND POWER

21:29

A box is being pushed horizontally on a smooth surface by a 10N force [WEP1] Q29

A man lifts a box of mass 2 kg vertically upwards by 3m [WEP1] Q30

A 1000 kg motorcar travels at a constant speed of 30 m/s [WEP1] Q31

A 1000 kg motorcar travels at a constant speed of 30 m/s [WEP1] Q31 Go deeper

A motor car of mass 500 kg generate a power of 1000W [WEP1] Q32

A motor car of mass 500 kg generates a power of 10000W (resistance on the motor car is 200 N) [WEP1] Q33

A 100 W spotlight has an efficiency of 40% [WEP1] Q34

The speed time graph shows the motion of a motorcar on a level road within a 10s duration [WEP1] Q35

Mixed Work Energy Power Questions

35:00

A 100 g mass drops from a 10m building (finding kinetic energy) [WEP1] Q36

A 100 g mass drops from a 10m building (finding speed) [WEP1] Q37

A worm of mass 2g crawls up a flight of steps from point A to point B [WEP1] Q38

A worm of mass 2g crawls up a flight of steps from point A to point B (with friction) [WEP1] Q39

A bullet hits a target board at a speed of 300 m/s. [WEP1] Q40

A mass of 2kg is suspended by a 1.0m string and is set free at point A [WEP1] Q41

A 3kg mass is being pulled along a horizontal bench at a constant speed of 5 m/s by a 10 N horizontal force [WEP1] Q42

A bullet leaves the vertical barrel of a rifle and reaches a height of 720m [WEP1] Q43

A car of mass M has an engine which can deliver power P [WEP1] Q44

A block of mass 1kg has a speed of 20 m/s at a point A [WEP1] Q45

A bullet leaves the vertical barrel of a rifle and reaches a height of 720 m [WEP1] Q46

A cable car of mass 200 kg travels up a hill from an altitude 1030 m to an altitude of 1150 m [WEP1] Q47

A block resting on a smooth horizontal floor is being pushed by a constant horizontal force. [WEP1] Q48

A 1 kg mass and a 5 kg mass are held at a position along the ramps as shown [WEP1] Q50

Extra Questions Set A

53:48

A mass hangs on a string fixed at point P. It starts from position 1 and swings to the furthest position on the opposite side, position 2. [WEP 2] Set A Q1

A man standing at the top of a cliff throws a stone. Which forms of energy does the stone have at X and at Y? [WEP 2] Set A Q2

A rubber ball is dropped from a height of 2 m on to a table. Whilst in contact with the table, some of its energy is converted into internal energy. What is the highest possible point the ball could reach after bouncing? [WEP 2] Set A Q3

A ball is released from rest and rolls down a track from the position shown. What is the furthest position the ball could reach? [WEP 2] Set A Q4

The graph shows how the height above the ground of a bouncing ball changes with time. Which statement explains why the height of each peak decreases with time? [WEP 2] Set A Q5

A workman rolls a barrel of weight 2000 N up a plank of length 2.00 m and on to a lorry. The back of the lorry is 0.80 m above the horizontal surface of the road. What is the work done on the barrel against gravity? [WEP 2] Set A Q6

A 2 kg mass is moving at constant speed. The kinetic energy of the mass is 400 J. What is the speed of the mass? [WEP 2] Set A Q7

An object is lifted vertically 2.0 m and held there. If the object weighs 90 N, how much work was done in lifting it? [WEP 2] Set A Q8

A 500-kg elevator is pulled upward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the weight of the elevator? [WEP 2] Set A Q9

A 15.0-kg object is moved from a height of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in gravitational potential energy? [WEP 2] Set A Q10

A boy holds a 40-N weight at arm's length for 10 s. His arm is 1.5 m above the ground. The work done by the force of the boy on the weight while he is holding it is: [WEP 2] Set A Q11

A 2-kg object is moving at 3 m/s. A 4-N force is applied in the direction of motion and then removed after the object has traveled an additional 5 m. The work done by this force is: [WEP 2] Set A Q12

A wooden block of mass 30 kg is pulled up a rough inclined plane at a constant speed by a force of 70 N. [WEP 2] Set A Q13

Hydroelectric, tidal and fossil fuels are three sources of energy. Which of these are renewable energy sources? [WEP 2] Set A Q14

Which represents the main energy changes that take place in a coal-fired power station? [WEP 2] Set A Q15

In a hydroelectric power station, water from a reservoir falls down a long pipe before entering the turbines. The turbines then turn the generator. What is the overall energy conversion? [WEP 2] Set A Q16

Which type of power station does not use steam from boiling water to generate electricity? [WEP 2] Set A Q17

Which type of power station does not use steam from boiling water to generate electricity? [WEP 2] Set A Q18

The diagram shows water stored behind a dam. The water flows to a turbine and turns a generator. Which sequence for the conversion of energy is correct? [WEP 2] Set A Q19

Which process in the Sun produces energy? [WEP 2] Set A Q20

A large electric motor is used to lift a container off a ship. Which of the following values are enough to allow the power of the motor to be calculated? [WEP 2] Set A Q21

A girl of weight 500 N runs up a flight of stairs in 10 seconds. The vertical height of the stairs is 5 m. What is the average power developed by the girl? [WEP 2] Set A Q22

Four students exercise in a gym. Which student does the most work? [WEP 2] Set A Q23

When a 300 N force is applied to a box weighing 600 N, the box moves 3.0 m horizontally in 20 s. What is the average power? [WEP 2] Set A Q24

A boy and a girl run up a hill in the same time. The boy weighs more than the girl. Which statement is true about the power produced? [WEP 2] Set A Q25

A worker is lifting boxes of identical weight from the ground onto a moving belt. At first, it takes him 2 s to lift each box. Later in the day, it takes him 3 s. Which statement is correct? [WEP 2] Set A Q26

Four people of equal weight on a beach use different routes to get to the top of a sea wall. Which person produces the greatest average power? [WEP 2] Set A Q27

A man of mass 80 kg is raised by a lift of 500 kg at a constant speed of 2.0 ms-1. What is the power of the lift’s motor? (Acceleration due to gravity = 10 ms-2) [WEP 2] Set A Q28

A small electric motor is used to raise a weight of 2.0 N at constant speed through a vertical height of 80 cm in 4.0 s. Assuming that the motor is 100% efficient, what is the electrical power supplied to the motor? [WEP 2] Set A Q29

Initially, four identical uniform blocks, each of mass m and thickness h, are spread on a table. How much work is done on the blocks in stacking them on top of one another? [WEP 2] Set A Q30

Which formula gives the efficiency of an energy conversion? [WEP 2] Set A Q31

The input power to a motor is 300 W. In 20 s it lifts a load of 400 N through a height of 6.0 m. What is the efficiency of the motor? [WEP 2] Set A Q32

A car is driven along a level road. The total energy input from the petrol is 60 kJ, and the car wastes 45 kJ of energy. What is the efficiency of the car? [WEP 2] Set A Q33

Energy from petrol is used to operate an engine. The engine drives a generator, which produces electrical energy. What is the overall efficiency of the process? [WEP 2] Set A Q34

A crane lifts a weight of 1000 N through a vertical height of 30 m. It uses 60 000 J of energy. What is the efficiency of the crane? [WEP 2] Set A Q35

A crane lifts a load of 1000 N through a vertical height of 3.0 m in 10 s. The input power to the crane is 500 J/s. What is the efficiency of the crane? [WEP 2] Set A Q36

Extra Questions Set B

77:40

The diagram below represents a 3.0-kilogram mass being moved at a constant speed by a force of 6.0 Newtons. [WEP 2] Set B Q1

The diagram below shows a 20N force pulling an object up a hill at a constant rate of 2 meters per second. [WEP 2] Set B Q2

A student rides a bicycle up a 30.º hill at a constant speed of 6.00 meters per second. The combined mass of the student and bicycle is 70.0 kilograms. What is the kinetic energy of the student-bicycle system during this ride? [WEP 2] Set B Q3

A cart of mass m traveling at speed v has kinetic energy KE. If the mass of the cart is doubled and its speed is halved, the kinetic energy of the cart will be [WEP 2] Set B Q4

Which cart shown below has the greatest kinetic energy? [WEP 2] Set B Q5

An object moving at a constant speed of 25 meters per second possesses 450 joules of kinetic energy. What is the object’s mass? [WEP 2] Set B Q6

Which graph best represents the relationship between the kinetic energy, KE, and the velocity of an object accelerating in a straight line? [WEP 2] Set B Q7

The diagram below shows an object at A that moves over a frictionless surface from A to E. The object has a mass of M. [WEP 2] Set B Q8

The diagram below shows block A, having mass 2m and speed v, and block B having mass m and speed 2v. Compared to the kinetic energy of block A, the kinetic energy of block B is [WEP 2] Set B Q9

If the direction of a moving car changes and its speed remains constant, which quantity must remain the same? [WEP 2] Set B Q10

The graph below represents the velocity-time relationship for a 2.0-kilogram mass moving along a horizontal frictionless surface. The kinetic energy of the mass is greatest during interval [WEP 2] Set B Q11

An inclined plane is 10 m long and is elevated 5 m on one end as shown. Starting from rest at the top of the incline, a box weighing 100 N accelerates down the incline at a rate of 2.5 m s-2 [WEP 2] Set B Q12

The diagram below shows a cart held motionless by an external force F on a frictionless incline. [WEP 2] Set B Q13

A 2.0-kilogram mass is placed on a frictionless track at point A and released from rest. Assume the gravitational potential energy of the system to be zero at point E. [WEP 2] Set B Q14

Which graph best represents the relationship between potential energy (PE) and height above ground (h) for a freely falling object released from rest? [WEP 2] Set B Q15

A simple pendulum has a 2.0-kilogram bob and a length of 10. meters. The pendulum is released from rest at position 1 and swings without friction through position 4 [WEP 2] Set B Q16

As the pendulum swings from position A to position B as shown in the diagram below, what is the relationship of kinetic energy to potential energy? [Neglect friction.] [WEP 2] Set B Q17

Three people of equal mass climb a mountain using paths A , B, and C shown in the diagram below. Along which path(s) does a person gain the greatest amount of gravitational potential energy from start to finish? [WEP 2] Set B Q18

A 10-kilogram block starts from rest at point A and slides along the track. What is the approximate speed of the block at point B? [WEP 2] Set B Q19

Which graph best represents the relationship between the gravitational potential energy of a freely falling object and the object’s height above the ground near the surface of Earth? [WEP 2] Set B Q20

How much work is done on a downhill skier by an average braking force of 9.8 × 102 Newtons to stop her in a distance of 10 meters? [WEP 2] Set B Q21

A box is pushed to the right with a varying horizontal force. The graph below represents the relationship between the applied force and the distance the box moves. [WEP 2] Set B Q22

As shown in the diagram below, a child applies a constant 20-newton force along the handle of a wagon which makes a 25° angle with the horizontal. [WEP 2] Set B Q23

A box is dragged up an incline a distance of 8 meters with a force of 50 Newtons. If the increase in potential energy of the box is 300 joules, the work done against friction is [WEP 2] Set B Q24

In the diagram below, 55 joules of work is needed to raise a 10 N weight 5.0 m. How much work is done to overcome friction as the weight is raised? [WEP 2] Set B Q25

A block weighing 15 N is pulled to the top of an incline that is 0.20 meter above the ground, as shown below. [WEP 2] Set B Q26

A constant force is used to keep a block sliding at constant velocity along a rough horizontal track. As the block slides, there could be an increase in its [WEP 2] Set B Q27

As shown in the diagram below, a student exerts an average force of 600. newtons on a rope to lift a 50.0-kilogram crate a vertical distance of 3.00 meters. [WEP 2] Set B Q28

A motor has an output of 1,000 watts. When the motor is working at full capacity, how much time will it require to lift a 50-newton weight 100 meters? [WEP 2] Set B Q29

A student running up a flight of stairs increases her speed at a constant rate. Which graph best represents the relationship between work and time for the student's run up the stairs? [WEP 2] Set B Q30

A force of 70 Newtons must be exerted to keep a car moving with a constant speed of 10 meters per second. What is the rate at which energy must be supplied? [WEP 2] Set B Q31

A boat weighing 9.0 × 102 N requires a horizontal force of 6.0 × 102 Nto move it across the water at 1.5 × 101 m/s. The boat’s engine must provide energy at the rate of [WEP 2] Set B Q32

If a boy of mass 90 kg takes 3 minutes to run up a flight of 60 steps of height 20 cm each, what is his average power? [WEP 2] Set B Q33

A force of 5 N exerted on an object causes it to accelerate from a velocity of 0 m s-1 to 8 m s-1 in 10 s. Determine the power of this force. [WEP 2] Set B Q34 method 1

A force of 5 N exerted on an object causes it to accelerate from a velocity of 0 m s-1 to 8 m s-1 in 10 s. Determine the power of this force. [WEP 2] Set B Q34 method 2

A baseball bat strikes a ball with an average force of 2.0 × 104 N. If the bat stays in contact with the ball for a distance of 5.0 × 10–3 meter, what kinetic energy will the ball acquire from the bat? [WEP 2] Set B Q35

Sixteen joules of work was required to lift a 2.0-kilogram object from the floor to a table. How much potential energy was gained by the 2.0-kilogram object? [WEP 2] Set B Q36

In the diagram below, an average force of 20. Newtons is used to pull back the string of a bow 0.60 meter. As the arrow, leaves the bow, its kinetic energy is [WEP 2] Set B Q37

At a height of 10 meters above the earth's surface, the potential energy of a 2-kilogram mass is 196 joules. After the mass which starts at rest falls 5 meters, its kinetic energy will be [WEP 2] Set B Q38

When object M is swung to a height of h and released, it passes through the rest position at a speed of 10 meters per second. The height h from which the object was released is approximately [WEP 2] Set B Q39

The diagram represents a 1.00 kilogram object being held at rest on a frictionless incline. [WEP 2] Set B Q40

A ball of mass 400 g rolls down a hill 2.0 m above the bottom of the hill, the speed of the ball is 3.0 m/s. [WEP 2] Set B Q41

The wrecking crane shown below is moving toward a brick wall which is to be torn down. At what point in the swing of the wrecking ball should the ball make contact with the wall to make a collision with the greatest kinetic energy? [WEP 2] Set B Q42

An electric motor is required to haul an object of weight 600 N up a vertical height of 100 min 2.0 minutes. What will be the electrical power required if the overall efficiency of the motor is 80%? [WEP 2] Set B Q43

The motor which drives a lift is working at 80% of its maximum power. The mass of the lift and its load is 500 kg and they are moving vertically upwards at a constant speed of 2 ms-1. [WEP 2] Set B Q44

A motorcar of mass 500 kg generates a power of 10,000 W. How much time does the motorcar need to accelerate from a speed of 10 m s-1 to 20 m s-1? [WEP 2] Set B Q45

Extra Questions Set C

33:56

A motorcar of mass 500 kg generates a power of 10,000 W. How much time does the motorcar need to accelerate from a speed of 10 m s-1 to 20 m s-1? [WEP 2] Set C Q1

A pendulum bob, swinging down swiftly is obstructed by a nail. Neglecting friction, the bob will then swing up to point [WEP 2] Set C Q2

A ball is allowed to roll along an undulating plane as shown. It is at rest at R. Neglecting air resistance and assuming the plane is smooth, [WEP 2] Set C Q3

On braking, 500 kJ of thermal energy was produced when a vehicle of total mass 1 600 kg was brought to rest on a level road. The speed of the vehicle before the brakes were applied was [WEP 2] Set C Q4

Walking up the top of the steep slope usually seems to be easier if a zigzag path is used instead of climbing by the steepest route. Why is this so? [WEP 2] Set C Q5

An electric motor is used to lift a 5 N load through 3 m as shown in the diagram. The total electrical energy used by the motor is 27 J. What amount of energy is wasted by the motor ? [WEP 2] Set C Q6

A 0.2 kg mass is thrown vertically upwards so that it reaches a height of 3 m above the point of projection. What is its kinetic energy when it is 2 m above the point of projection? [WEP 2] Set C Q7

A crate is pushed along a horizontal surface by a force of 80 N. The frictional force opposing the motion is 60 N. How much of the work done is converted into kinetic energy and internal energy of the crate? [WEP 2] Set C Q8

A cyclist travels along a horizontal track at constant speed. The work done by the cyclist is equal to [WEP 2] Set C Q9

A lorry of mass 10 000 kg takes 5000 kg of sand to the top of a hill 50 m high, unloads the sand and then returns to the bottom of the hill. The gravitational field strength is 10 N/kg. What is the overall gain in potential energy? [WEP 2] Set C Q10

A wooden block of mass of 30 kg is pulled up a rough inclined plane at a constant speed by a force of 70 N parallel to the plane. When the distance moved along the plane is 12 m, the increase in height is 1.0 m. [WEP 2] Set C Q11

An object of mass 20 kg is pulled up a slope of 15 m long. The frictional force between the object and the slope is 30 N. The minimum work done by the pulling force is [WEP 2] Set C Q12

A weight is to be lifted from a level X to a high level Y along different paths labelled L, M and N. [WEP 2] Set C Q13

How much work is done when a person raises a 3 kg lead ball by a vertical distance of 1.5 m and throws it horizontally with an initial velocity of 10 m s-1 ? [WEP 2] Set C Q14

A girl weighing 400 N takes 4.0 s to run up the stairs as shown in the diagram below. Which of the following gives the values of her average speed and power? [WEP 2] Set C Q15

A lorry of mass 2000 kg has an engine which can deliver a maximum power of 50 kW. What is the minimum time in which the car can be accelerated from rest to a speed of 100 km h-1 on level ground? [WEP 2] Set C Q16

A car of mass M = 800 kg decelerates from 80 km h-1 to rest in 12 5. At what average rate must the braking surfaces lose heat if their temperature is not to rise significantly? [WEP 2] Set C Q17

An electric motor runs with a steady input of 250 V and 4 A while raising a load of 1 000 N. Assuming that the motor and transmission is 100 % efficient, how much time is taken to lift the load vertically through a distance of 10 m? [WEP 2] Set C Q18