Problem : A baseball player releases a ball with [tex]v_0= 100 ft/sec[/tex] at an angle of [tex]\theta= 30 degrees[/tex]. Determine the radius of curvature of the trajectory (a) just after release and (b) at the apex. For each case compute the time rate of change of the speed.(adsbygoogle = window.adsbygoogle || []).push({});

I really wasn't sure how to do the problem, so I sort of just guessed at alot of things. So any help would be great. But this is what I did.

I assumed the only acceleration after the ball was thrown was due to gravity.

so I got

[tex] a_n=-32.2*cos(30)[/tex] [tex]a_t=-32.2*sin(30)[/tex]

then I used [tex] a_n=\frac{v^2}{\rho}[/tex] to solve for the curvature [tex]\rho[/tex] for when the ball was just released I got [tex]\rho = 358.6 ft[/tex] . Then I used [tex]\beta'=\frac{100}{\rho}[/tex] to solve for the angular rate.

I wasnt sure on how to solve (b) so I just assumed that the angle between [tex]\theta[/tex] and the x- axis would be 0 degrees since the apex is the highest point and I guessed that would be when the ball would stop moving up and start going down.

So I got

[tex]a_n = -32,2 ft/s^2[/tex]

then used

[tex]a_n=v*\beta'[/tex] to solve for v at the apex using the the angular rate i got earlier for beta'.

I got [tex]v=115.4ft/s[/tex]

then using the v and [tex]a_n[/tex] I solved for [tex]\rho[/tex] using the equation [tex] a_n=\frac{v^2}{\rho}[/tex]

I got [tex]\rho= 413 ft[/tex]

I'm definitely not confident with this answer, it's the first time I've done a problem like this, and I'm not sure if everything I did and assumed was legal.

Thanks in advance for any help.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Homework help (normal and tangential coordinate problem)

Can you offer guidance or do you also need help?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**