I answered the questions and I think i have them right, this is new stuff though so I just wanna make sure i understand everything, if someone could confirm it would put a smile on my face like this ->(adsbygoogle = window.adsbygoogle || []).push({});

During a serve, a tennis player hits the ball horizontally with a force of 500 N, without putting a spin on it. The 100g ball leaves the racket at a velocity of 40 m/s

a) calculate the time during which the ball was in contact with the player's racket

So i use the impulse formula:

Force * Time = Mass * delta velocity

500 * t = 0.1(kg) * 40

t = 0.008s

b) During its displacement, the ball slows down due to the effect of air resistance. Assuming that the frictional force of 5 N is constant, calculate the ball's average horizontal deceleration in the first second of its flight.

Here i'll find the difference between the initial acceleration and the one after 1 second:

Force = Mass * Acceleration

500 = 0.1 * a

a = 5000m/s^2

Fnet = Fa - Ff = ma

500 - 5 = 0.1 * a

a = 4950m/s^2

So the horizontal deceleration is -50m/s^2

c) Calculate the ball's horizontal velocity when it hits the ground, on the other side of the net, at a distance of 12m from the server.

(Delta V)^2 = 2ad

V2^2 - 1600 = 2 * -50 * 12

V2 = sqr(400) = 20m/s

Thanks in advance

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# Homework Help: Tennis player hits the ball velocity help

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