# Homework Help: Equations of Motion

1. Mar 3, 2005

### ][nstigator

Two physics students conduct the following experiment from a very high bridge. Thao drops a 1.5kg shot put from a vertical height of 60m while at exactly the same time Benjamin throws a 100g mass with an initial downwards velocity of 10 m/s from a point 10m above Thao.

At what time will the 100g mass overtake the shot-put?

2. Mar 3, 2005

### Jayboy

There are two ways to set up this problem:

1. Use the usual equations of motion for body 1 (the heavier mass) and 2 (the lighter mass).

$$S(1) = 70 -10t - 0.5gt^2$$
$$S(2) = 60 - 0.5gt^2$$

Then solve for the time when their positions are the same.

2. Since the acceleration of both objects are the same under gravity, you may notice that this can be reduced to a simple relative velocity problem.

3. Mar 3, 2005

### dextercioby

And one more thing,though you're give the masses,you may very well neglect air friction.The fact that they give you the masses was just for identification.

Daniel.