Fsica 11 de secundaria

1 Profesor: Javier Trigoso T.

01. A laborer on a building site lifts heavy concrete blocks onto a lorry.

Lighter blocks are now lifted the same distance in the same time.

What happens to the work done in lifting each block and the power

exerted by the laborer?

work done in

lifting each block

power exerted

by laborer

A decreases decreases

B decreases remains the same

C increases increases

D remains the same increases

02. 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?

A. The boy produces more power.

B. The girl produces more power.

C. They both produce the same power.

D. I t is impossible to tell who produces more power.

03. Which of the following is not a unit for power?

A. Joule second B. Watt C. Newton meter per second D. Horsepower

Fsica 11 de secundaria

2 Profesor: Javier Trigoso T.

04. A laborer on a building site lifts a heavy concrete block onto a lorry. He

then lifts a light block the same distance in the same time.

Which of the following is true?

work done in lifting

the blocks

power exerted

by laborer

A less for the light block less for the light block

B less for the light block the same for both blocks

C more for the light block more for the light block

D the same for both blocks more for the light block

05. A force F moves a load from the bottom of a slope to the top.

The work done by the force depends on the size of the force, and on a

distance.

What is the distance?

A. p B. q C. r D. p + q

06. The table shows the times taken for four children to run up a set of stairs.

Which childs power is greatest?

mass of child/kg time/s

A 40 10

B 40 20

C 60 10

D 60 20

07. An electric pump is able to lift 200 kg of water vertically up to a height of

30 m above the ground in 50 s. What is the power of the machine?

A. 0.12 kW B. 6.0 W C. 1.2 kW D. 300 kW

Fsica 11 de secundaria

3 Profesor: Javier Trigoso T.

08. A 10 kg object experiences a horizontal force which causes it to

accelerate at 5 m/s2, moving it a distance of 20 m, horizontally. How

much work is done by the force?

A. 1 000 Newtons B. 1 000 Joules

C. 1000 Watts D. 1 000 Kilograms

09. A worker is lifting boxes of identical weight from ground onto a moving

belt.

A first, it takes him 2 s to lift each box. Later in the day, it takes him 3 s

Which statement is correct?

A. Later in the day, less work is done in lifting each box

B. Later in the day, more work is done in lifting each box

C. Later in the day, less power is developed in lifting each box

D. Later in the day, more power is developed in lifting each box

10. A 10 kg weight is suspended in the air by a strong cable. How much work

is done, per unit time, in suspending the weight?

A. 10 J B. 100 J C. 1 J D. 0 J

11. A person of mass 70 kg runs up a flight of stairs with a vertical height of

5m. Of the trip takes 7s to complete, calculate the persons power.

A. 5 W B. 50 W C. 500 W D. 5000 W

Questions 12-15 A lift motor has to move a fully laden lift 4m between floors in 1.5s.

The lift has a mass of 1 850 kg (ignore friction).

12. Calculate the weight of the fully laden lift

A. 185 N B. 1 850 N C. 18 500 N D. 185 000 N

13. What is the upward force in the cable when the lift is moving at a

constant speed?

A. 185 N B. 1 850 N C. 18 500 N D. 185 000 N

14. What is the work done by the motor?

A. 74 000 J B. 7 400 J C. 740 J D. 74 J

15. What is the minimum power of the motor to raise the lift at a steady

speed?

A. 49 333 W B. 4 933 W C. 4 933 W D. 493 W

Fsica 11 de secundaria

4 Profesor: Javier Trigoso T.

Questions 16-19 Charlie takes 11 minutes to walk up a hill meters high. His weight is 550 N

16. How much work does he do in climbing the hill?

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17. How many seconds does he take to the climb the hill?

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18. What the power is developed by his muscles as he climbs?

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19. I f he runs up the hill his muscles can develop 500 Watts. How long will it

take him to get to the top of the hill?

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20. A student with a weight of 600 N runs up the flight of stairs shown in the

diagram in 4 seconds. Calculate the students power.

A. 600 W B. 750 W C. 1 500 W D. 3 000 W