# Physics help

1. Oct 8, 2004

### buffgilville

Can anyone tell me if my answers are right or wrong? thanks

A boy with a slingshot wants to hit a can on top of a pole. The can is a distance of 15 meters from the boy at an elevation of 30 degrees above the horizontal. The boy aims the slingshot directly at the can and projects a stone with a speed of 22 meter/second. It misses the can. (We want to find out bad the aim was.)

a) Find the x- and y- components of the displacement of the can from the child.

12.99 x + 7.50 y

b) What is the initial velocity of the stone?

19.05 x + 11.0 y

c) When does the stone pass directly below the can?

0.682 seconds

d) Find the height differential between the can and the path of the stone.

2.28 meters

e) Find the range of the stone (i.e. where it lands).

14.0 meters

2. Oct 9, 2004

### BLaH!

Look over (d) and (e) more carefully. The rest of your answers look good. For (d) you will need to use:

$$y = v_{0y}t - \frac{1}{2}gt^2$$

For part (e) you can use the same equation and solve for t when y = 0. That will give you the total time of flight. You can then find the range via

$$x = v_{0x}t$$