(a)
consider the motion of the tennis ball. lets assume the velocity of the tennis ball going towards the racket as positive and velocity of tennis ball going away from the racket as negative.
m = mass of the tennis ball = 60 g = 0.060 kg
v₀ = initial velocity of the tennis ball before being hit by racket = 20 m/s
v = final velocity of the tennis ball after being hit by racket = - 39 m/s
ΔP = change in momentum of the ball
change in momentum of the ball is given as
ΔP = m (v - v₀)
inserting the above values
ΔP = (0.060) (- 39 - 20)
ΔP = - 3.54 kgm/s
hence , magnitude of change in momentum : 3.54 kgm/s
Upward and downward forces cancel out. Net force is 8 newtons to the right
Answer:
.
Explanation:
Let denote the absolute temperature of this object.
Calculate the value of before and after heating:
.
.
By the Stefan-Boltzmann Law, the energy that this object emits (over all frequencies) would be proportional to .
Ratio between the absolute temperature of this object before and after heating:
.
Therefore, by the Stefan-Boltzmann Law, the ratio between the energy that this object emits before and after heating would be:
.