(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
Answer:
a) 
b) west end of the bar is positive.
Explanation:
Given:
- emf induced in the bar,

- length of the bar,

- velocity of the bar at the given instant,

(a)
The magnitude of the horizontal component of the Earth's magnetic field(B):
We know:



(b)
Using Fleming's left hand rule we determine that the current is flowing towards east end of the bar i.e. west end of the bar is positive.
Answer:
23.5 m/s
Explanation:
The velocity of the car in decelerated motion is given by
v = u + at
where
v = 0 is the final velocity
u is the initial velocity
a is the acceleration of the car
t = 3.0 s is the time it takes for the car to stop
The acceleration of the car is given by the frictional force, which is the only force acting on the car along the direction of motion, so:

where
is the coefficient of friction
Solving the previous equation for u, we find the initial velocity:

49 J is the total kinetic energy. If a bowling ball of mass 7.3 kg and radius 9.6 cm rolls without slipping down a lane at 3.1 m/s. Kinetic energy is the energy an bowling ball has because of its motion.
Given: m = 7.3 Kg ; r = 9.4 cm = 0.094 m ; v = 3.1 m
Now total kinetic energy in this case is given by KE = Kinetic energy due to rotation + Kinetic energy due to translation
i,e KE = 1/2*m*v2 + 1/2*I*ω2 where I is the moment of inertia of the bowling ball about it's center and ω is the angular velocity
Now for pure rotation (without slipping) v = rω
also for the ball (solid sphere) I = 2/5*m*r2
Hence our kinetic energy becomes
KE = 1/2*m*v2 + 1/5*m*v2 = 7/10*m*v2
so KE = 0.7*7.3*(3.1)2 = 49.10 J = 49 J
Learn more about kinetic energy here
brainly.com/question/12669551
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