Physics is too hard for me? Please help?

Question

The fastest recorded pitch in Major League Baseball, thrown by Nolan Ryan in 1974, was clocked at 162.3 km/h (100.8 mi/h). If a pitch were thrown horizontally with this velocity, how far would the ball fall vertically by the time it reached home plate, 18.3 m (60.0 ft) away?
m

Answer 1

Nice. I see that you, too, are using the College Physics book by Serway and Faughn.

We first convert 162.3 km/h into m/s for convenience. It should be about 45.08 m/s. We have two motions to consider, one in the x direction and one in the y. You must recognize that the x direction has NO acceleration, but the y does. We will solve to see how long it takes to get to the base. We only need a simply d=rt formula.

Distance = Rate * Time

We have the distance (18.3 m) and we have the rate (45.08 m/s). Just plug it into the equation to find time.

18.3 = 45.08 * Time in seconds
Time = 0.406 seconds

Now that we know how long it took to get to the base, we can forget everything we know about x direction stuff (except for the time, of course). Let's use the following equation for the y direction.

y = (intial velocity in the y direction)(time) + (0.5*acceleration*time^2)
We know that there was no initial velocity in the y direction, because we did not have any (or rather, consider any) up and down motions we he pitched the ball. So the first part is cancelled out, and we have the remaining equation.

y = (0.5*acceleration*time^2)
acceleration in y direction = gravity = 9.8 m/s/s
time = 0.406 sec (found in the first part)

y = 81 cm.

I hope this answered your question.

Answer 2

t= 18.3/(162.3*1000) *3600 =0.4059s
Vertical fall = 1/2*9.8 *(0.4059)^2 =0.81m