Power
Grade 11 Science Worksheet
Circle the best answer, or write your answer on the line.
A motor drags a 40 kg crate 6 m up a 30° ramp at steady speed in 8 s. Friction on the crate is 50 N. What power does the motor supply, Ari?
A motor drags a 25 kg crate 4 m up a 30° ramp at steady speed in 5 s. Friction on the crate is 30 N. What power does the motor supply, Bo?
A motor drags a 60 kg crate 5 m up a 30° ramp at steady speed in 10 s. Friction on the crate is 40 N. What power does the motor supply, Esme?
A motor supplies a steady 250 W as a cart climbs a slope. Its speed falls from 5 m/s to 2.5 m/s. What happens to the pull force, Kira?
- It halves, from 50 N to 25 N
- It stays at 50 N
- It doubles, from 50 N to 100 N
An elevator cabin of 800 kg rises at a steady 2 m/s while a 600 kg counterweight falls at 2 m/s. Ignoring friction, what power must the motor supply, Luz?
- 3,920 W
- 11,760 W
- 15,680 W
- 27,440 W
A pump lifts 30 kg of water every second through 10 m at steady speed. What is the least power it must supply, Milo?
- 2,940 W
- 294 W
- 300 W
- 29,400 W
Motor X draws 500 W and is 60% efficient. Motor Y draws 400 W and is 80% efficient. Which delivers more useful power, and by how much, Pia?
- Motor X, by 100 W
- Motor Y, by 20 W
- Motor Y, by 100 W
- Motor X, by 20 W
A 1,200 kg car speeds up from rest to 20 m/s in 8 s. Ignoring draw a line, what is its average power, Ren?
- 30 kW
- 60 kW
- 3 kW
- 15 kW
A 1,200 kg car gains speed at a steady 2.5 m/s². Ignoring draw a line, what power does the engine supply at the moment it reaches 20 m/s, Tala?
- 60 kW
- 480 kW
- 24 kW
- 30 kW
A car speeds up from rest under a constant net force. Compared with its power at 8 s, how large is its power at 4 s, Zee?
- A quarter as large
- The same, since the force is constant
- Half as large