Work, power and Energy

If you carry a 5 kg box across the room at a constant velocity

• you do no work.

• you do some work.

• you do negative work.

• Cannot be determined.

On a work vs time graph, you can calculate the power by

• the area.

• the y-axis.

• the y-intercept.

• the slope.

How much power was generated from 0-4 seconds?

• 1100 W

• 4 W

• 267 W

• 1600 W

How much work is done?

• 9 J

• 18 J

• 27 J

• 36 J

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

• 81 W

• 27 W

• 3 W

• 6 W

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

What kind of energy(ies) does the car have at position A? The ground is h=0.

• KE

• KE + PE

• PE

• KE - PE

The work-kinetic energy theorem says that the net work done by all the forces acting on an object is equal to the change in the object's _____.

• mechanical energy
• work
• momentum
• kinetic energy

The % energy efficiency of an appliance is

• total energy input/ useful energy output x 100

• useful energy output /total energy input x100

• total energy input x useful energy input x100

• useful energy output /total energy input x50

If a system is isolated, the total energy of the system

• Increases constantly.

• Decreases constantly.

• Is constant.

• Depends on the work done on the system.

• Depends on the work done by the system.