Question

Five marbles roll down a ramp. Each marble reaches the bottom of the ramp at a speed of 3 meters/second. Which marble has the highest kinetic energy at the bottom of the ramp? The table lists the mass of each marble
marble 1 10g
marble 2 is 20 g
marble 3 is 25
marble 4 is 40g
marble 5 is 5

Answer 1

The smallest marble has the most kinetic energy therefore it would be the correct answer

Answer 2

Answer: marble 4 (40g)

Explanation:

The kinetic energy of an object is given by:

$E_k = \frac{1}{2}mv^2$

where

m is the mass of the object

v is its speed

In this problem, all the marbles have same speed (v=3 m/s), so their difference in kinetic energy depends on their different mass only. In particular, we see that the kinetic energy is proportional to the mass: therefore, the larger the mass, the more the kinetic energy.

For this reason, the ball with the greatest kinetic energy is marble 4, which has the greatest mass (40 g). Its kinetic energy is given by

$E_k=\frac{1}{2}(0.04 kg)(3 m/s)^2=0.18 J$