CIE iGCSE Co-Ordinated Science P1.6.4 Power Exam Style Questions Paper 1
Question
Four different kettles contain different masses of water. They are used to heat the water from 20 °C to 100 °C. Each kettle takes a different amount of time to do this. Which kettle has the lowest useful power output?
| mass of water/g | time to heat water to 100 °C/minute | |
|---|---|---|
| A | 1000 | 3.0 |
| B | 1000 | 5.0 |
| C | 2500 | 3.0 |
| D | 2500 | 5.0 |
▶️Answer/Explanation
Answer: B) 1000 | 5.0
Explanation: Power output is inversely proportional to the time taken to heat the water. Kettle B takes the longest time (5.0 minutes) to heat the water, indicating the lowest power output.
Question
Four cars travel the same distance directly up the same steep hill. The weights of the cars and the times for their journeys are shown in the table. Which car develops the greatest power?
| Car | Weight of car / N | Time taken / s |
|---|---|---|
| A | 15,000 | 10 |
| B | 15,000 | 15 |
| C | 20,000 | 10 |
| D | 20,000 | 15 |
▶️Answer/Explanation
Answer: C
Explanation: Power is calculated using the formula \( P = \frac{W}{t} \), where \( W \) is the work done (which is equal to the weight of the car multiplied by the distance traveled) and \( t \) is the time taken. Since all cars travel the same distance, the car with the highest weight and the shortest time (Car C) will develop the greatest power.
Question
Two forklift trucks P and Q lift identical loads through the same vertical height.
Truck P takes a greater time than truck Q to lift the load.
Which statement is correct?
(A) Truck P does more work than truck Q.
(B) Truck P produces more power than truck Q.
(C) Truck Q does more work than truck P.
(D) Truck Q produces more power than truck P.
▶️Answer/Explanation
Ans: D
Question
A machine takes a certain time to do a certain quantity of work.
Which pair of changes must increase the power of the machine?
A decreasing the work done and decreasing the time taken
B decreasing the work done and increasing the time taken
C increasing the work done and decreasing the time taken
D increasing the work done and increasing the time taken
▶️Answer/Explanation
Ans : C
Question
A machine does a certain quantity of work in a certain time.
Which changes to the quantity of work done and to the time taken both decrease the power produced by the machine?
▶️Answer/Explanation
Ans: B
Question
The power rating of an electric kettle is 1500 W.
What does this mean?
(A) The kettle requires 1500 J to boil water.
(B) The kettle takes 1500 s to boil water.
(C) The kettle transfers 1500 J of energy every second.
(D) The weight of the kettle is 1500 N.
▶️Answer/Explanation
Ans: C
Question
A crane lifts a load of mass 300 kg through a height of 20 m in 1.0 minute. The gravitational field strength \( g \) is 10 N/kg. What is the average power output of the crane during this task?
A 600 W
B 1000 W
C 36 000 W
D 60 000 W
▶️Answer/Explanation
Answer: B 1000 W
Explanation: The work done by the crane is calculated as: work = force × distance = mass × gravitational field strength × height = 300 kg × 10 N/kg × 20 m = 60,000 J. Power is work divided by time, so power = 60,000 J / 60 s = 1000 W.
Question
Four cars travel up the same hill. They have different masses and take different times to travel up the hill. Which car is supplying the most useful power?
| mass of car/kg | time taken to travel up hill/s | |
|---|---|---|
| A | 1500 | 10 |
| B | 1500 | 20 |
| C | 3000 | 10 |
| D | 3000 | 20 |
▶️Answer/Explanation
Answer: C
Explanation: Power is calculated as work done divided by time. The car with the highest mass and the shortest time (car C) will be supplying the most useful power, as it is doing the most work in the least amount of time.
Question
Four cars are driven the same distance along a straight, horizontal road. The table shows the work done by the engine in each car and the time taken by each car.
Which engine produces the most power?
▶️Answer/Explanation
Answer: C
Explanation: Power is calculated as work done divided by time taken. Car C has the highest power output (100,000 J / 20 s = 5,000 W).