Explanation:
It is given that,
Mass of the ball, m = 0.06 kg
Initial speed of the ball, u = 50.4 m/s
Final speed of the ball, v = -37 m/s (As it returns)
(a) Let J is the magnitude of the impulse delivered to the ball by the racket. It can be calculated as the change in momentum as :

J = -5.24 kg-m/s
(b) Let W is the work done by the racket on the ball. It can be calculated as the change in kinetic energy of the object.


W = -35.1348 Joules
Hence, this is the required solution.
There are other forces at work here nevertheless we will imagine
it is just a conservation of momentum exercise. Also the given mass of the
astronaut is light astronaut.
The solution for this problem is using the formula: m1V1=m2V2 but
we need to get V1:
V1= (m2/m1) V2
V1= (10/63) 12 = 1.9 m/s will be the final speed of the astronaut after
throwing the tank.
Answer:
C. The information is always easily restored."
Explanation:
When the personal information stored digitally on a computer is accidentally
deleted, the data is even stored in the hard disk in various fragments until it is not permanently deleted. Hence the correct option will be "C. The information is always easily restored."