# Homework Help: Physics Question Speed/Time

1. Nov 25, 2012

### Debate123

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

A ball player hits a home run, and the baseball just clears a wall 20.9 m high located 131.0 m from home plate. The ball is hit an an angle of 35° to the horizontal, and air resistance is negligible. Assume the ball is hit at a height of 0.9 m above the ground.
(a) What is the initial speed?
m/s
(b) How much time does it take for the ball to reach the wall?
s
(c) Find the components of the velocity and the speed of the ball when it reaches the wall
vy,f = m/s
vx,f = m/s
vf = m/s

2. Relevant equations
vi(intial velocity)

3. The attempt at a solution
I got 8.5 seconds for the time but thats apparently not right and it's prohibiting me from further progress.

2. Nov 25, 2012

### tiny-tim

Welcome to PF!

Hi Debate123! Welcome to PF!

Show us your full calculations, and then we'll see what went wrong, and we'll know how to help!

3. Nov 25, 2012

### Debate123

Dx+Vxi*t
DX=Vx*CoS35.t
!3!+Vxcos35.tw
Vi+131?Cos35.tw

20.9+-4.9t^2+sin35/Cos35+.09
20.9=-4.9tw2+65.1385/.8191+.09
20.9=-4.9tw^2+91.727+0.9
20.9-92.627=tw^2
tw=sqrt71.727
tw=8.46(deemed wrong by my webassign)

4. Nov 25, 2012

### tiny-tim

i think you may have entered 113 instead of 131

5. Nov 25, 2012

### Debate123

I still don't know to fix my problem entirely, theres 5 parts and I can't even get 1

6. Nov 25, 2012

### Debate123

Can someone show me the time so I can finish the problem myself please?

7. Nov 25, 2012

### Debate123

NVM figured it put by myself
a) Initial ball speed: 41.7 m/s
b) Time for ball to reach wall: 3.81 s
c) x velocity-component: 34.2 m/s
y velocity-component: -13.4 m/s
Speed of the ball: 36.7 m/s