A 57g tennis ball is served at 45 m/s?
If the ball started from rest, what impulse was applied to the ball by the racket?
Impulse is in Ns (newton-seconds).
FΔt = mΔv
Impules = mΔv = 0.057kg (vf-vi) = 0.057kg (45m/s-0.0m/s) = (0.057kg (45m/s) = 2.565 kgm/s.
Just so you know, 1N = 1kgm/s^2
So, FΔt = (kgm/s^2)(s)=kgm/s
Impulse is product of force and time (I = F x t).
Now,we know that
since a=v/t so
now take "t" to the left side
F x t = mv
Impulse = mv = 0.057kg x 45m/s = 2.565Ns (answer)