Tha atmosphere has no effect on gravity.
Answer:
a) Resistivity=R.A/L
Here, R=500000ohm, L=1.6m, A=2pi* (0.14/2)*0.002 m2=0.00088.........we have converted quantities into SI units
Resistivity=R.A/L
=500000*0.00088/1.6 = 440/1.6= 275 ohm.meter
b) pskin/pinterior =275/4.8=57.3
For second part, correct option is (A), because cross section area is smaller.
Power is the energy transferred or "WORK DONE" in one second
(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
