Ch. 7: Which type of energy does a stretched spring contain?

Ch. 8 & 9: Which of the following improves the efficiency of a machine?

Ch. 8 & 9: Which of the following levers has the largest mechanical advantage?

Ch. 8 & 9: In the picture of the crowbar, which letter shows the fulcrum?

Four students run up the stairs in the time shown. Which student has the largest power output?

In the equation PE = mgh, what does the “g” mean?

Which requires more power – a person walking up stairs or a person running up stairs?

How much power is required to raise a 200-kg crate a vertical distance of 2 m in a time of 4 s?

P = W / t

If a charging elephant has kinetic energy, it must also have

A 5 N force is applied to a 3 kg ball to change its velocity from +9 m/s to +3 m/s. The impulse on the ball is ______ N*s.

Impulse = F*t

If an airbag changes a 60 kg person's speed from 40.0 m/s to 0.0 m/s, what impulse must act on the person?

Impulse = m*v

What impulse would be needed to stop a 1500 kg car traveling at 20 m/s?

Impulse = m*v

When two objects collide their motion changes. Why does this happen?

Select all the examples of collisions.

Select all the types of collisions.

Energy can be created and destroyed, but not transformed.

What is the efficiency of a machine if 55.3 J of work are done on the machine (work input), but only 14.3 J or work are done by the machine?

Efficiency = work output / work input x 100

Total energy = 350J
Useful energy = 70J

Workout the efficiency of this iphoneX.
 $efficiency\ =\ \frac{useful\ energy}{total\ energy\ in}\ \times100\%$  

This car needs 8600J of energy to power it. If 5000J is changed into useful energy, how much energy is wasted?

What is the efficiency of the machine if the input is 263 J and the output is 142 J?

Efficiency = Work output / work input x 100