Phy Y10Y11 Y10 C6 IGCSE Revision Energy Work Power 20231

A skier walks from the bottom of a ski slope to the top and gains 10000J of gravitational potential energy. She skis down the slope. At the bottom of the slope, her kinetic energy is 2000J

How much energy is dissipated in overcoming friction and air resistance as the skier moves down the slope?

• 2000J

• 8000J

• 10000J

• 12000J

A coal-fired power station generates electricity. Coal is burnt and the energy released is used to boil water. The steam from the water makes the generator move and this produces electricity. Which words are used to describe the energy stored in the coal and the energy of the moving generator?

• coal: chemical generator: hydroelectric

• coal : chemical generator: kinetic

• coal: geothermal

  generator: hydroelectric

• coal: geothermal

  generator: kinetic

Power is a _______ dependent quantity.

• Outlet

• Energy source

• Time

• Volume

The diagrams show four different athletes training by doing pull-ups.

Which athlete does the most work?

• 
• 
• 
• 

If it took 9 seconds for the object to move 6 meters, what's the power?

• 81 W

• 27 W

• 3 W

• 6 W

How high up is a 3200-kg plane if it has 960000 J of potential energy?

• 10 m

• 30 m

• 307200000 m

• 300 m

Answer explanation

PE = mgh

(Use g = 10 m/s² if you're in a hurry)

What is the mass of an object with 1200 J of PE when it is 5 meters above the ground?

• 10 kg

• 24 kg

• 100 kg

• 240 kg

A man of mass 50 kg jumps to a height of 1 m. His potential energy at the highest point is(g = 10 m/s²)

• (a) 500 J

• (b) 50 J

• (c) 5 J

• (d) 5000 J

What effect do external forces like an applied force, friction force, or drag force have?

• They have no effect on a system's mechanical energy.

• They convert kinetic energy into potential energy.

• They convert potential energy into kinetic energy.

• They convert between mechanical energy and other forms of energy to change the total mechanical energy of the system.

Answer explanation

A closed, isolated system will have the same mechanical energy after some change as before the change.

If there are external forces, then the mechanical energy of the system will change.

Power is a _______ dependent quantity.

• Outlet

• Energy source

• Time

• Volume