# Homework Help: Distance travelled by a thrown object

1. Jan 18, 2012

### Dberry

1. The problem statement, all variables and given/known data

The diagram to this problem is of a HILL as shown:

Point A
-
-
20m
-
-
------------------------50m------------------------- Point B

From ground level, a person at Point A throws a snowball horizontally to the right at 25 m/s. Where does the snowball land?

a) 10m to the left of Point B
b) At Point B
c) 12.5m to the right of Point B
d) 50m to the right of Point B

2. Relevant equations

According to the answer given (answer is B), the relevant equations are t=(2h/g)^(1/2) and d=vt

3. The attempt at a solution

The 4 linear motion equations I know are

x = x + vt + (1/2)at^2
v(initial) = v(final) + at
v(i)^2 = v(f)^2 + 2ax
v(avg) = (v(i) + v)/2

I don't know the time equation listed in the answer. Is it derived from one of these equations or is it a whole different equation? I'm confused about how I was supposed to know to solve this question basically...

2. Jan 18, 2012

### Staff: Mentor

if you dropped the ball how long does it take?

then use that time to compute how far it went.

3. Jan 18, 2012

### Dberry

I know I have to find time first, but if you read the comments I'm asking about the equation used. I have never seen it before and I'm confused about where it comes from. Is it derived from another equation?

4. Jan 18, 2012

### Staff: Mentor

s= 1/2 g t^2 with s being the height of point A