Solving Tennis Physics: Force & Acceleration

[Meowserkitty]

Homework Statement

A tennis racket (950 g) hits a tennis ball (110 g) with a force of 5000 N. What is the acceleration of the tennis ball? During the collision, with what force does the tennis ball hit the tennis racket? What is the acceleration of the tennis racket? (Remember that force and acceleration are vectors, so be careful with positive and negative signs. Assume the player let's go of the racket just after contact.)

Homework Equations

f = m*a

The Attempt at a Solution

5000=110a
a) 45.4 m/s2
b) -5000 N
c) 5000=950a
-5.3 m/s2

 

[oli4]

Hi Meowserkitty
Be careful with your units, 1N=1Kg/s²

 

[runningninja]

Hi Meowserkitty
Be careful with your units, 1N=1Kg/s²

Nope, 1N=(1kg(m))/s²
Also, whenever you see collisons, that just begs momentum. (p=mv)
Your answer was way too simplistic. Physics is (almost) never that easy, unfortunately.

 

[oli4]

Ah yes, sorry I forgot the m because I was looking at putting the bold tag around Kg first :)

 

[Meowserkitty]

Could you explain how I should go about this? Our physics teacher was gone all week and could not help us.

 

[oli4]

You just have to transform the mass expressed in g as expressed in Kg, that is, you divide it by 1000 :)

 

[Meowserkitty]

You just have to transform the mass expressed in g as expressed in Kg, that is, you divide it by 1000 :)

Other than that do I do the same thing I did? And would the rackets acceleration be negative?

 

[Meowserkitty]

Nope, 1N=(1kg(m))/s²
Also, whenever you see collisons, that just begs momentum. (p=mv)
Your answer was way too simplistic. Physics is (almost) never that easy, unfortunately.

We are not doing momentum yet

 

[oli4]

We are not doing momentum yet

Yes, you are :)
Maybe you didn't call it this way in class, but the Newton's law you are using is
"the force is the rate of change of momentum"
F=d(mv)/dt
As far as you are/will be concerned for a while, mass is constant, so that becomes
F=mdv/dt=ma :)