Answer:
V = 0.9 m/s
Explanation:
The parameters given are:
Initial velocity U = 6.4 m/s
Time t = 0.64s
Height h = 2.05 m
To find the final velocity, let us use third equation of motion
V^2 = U^2 - 2gH
Since the ball is going upward, g will be negative
Substitute all the parameters into the formula
V^2 = 6.4^2 - 2 × 9.8 × 2.05
V^2 = 40.96 - 40.18
V^2 = 0.78
V = sqrt( 0.78)
V = 0.883 m/ s
V = 0.9 m/ s approximately
Our values can be defined like this,



The problem can be solved for part A, through the Work Theorem that says the following,

Where
KE = Kinetic energy,
Given things like that and replacing we have that the work is given by
W = Fd
and kinetic energy by

So,

Clearing F,

Replacing the values


B) The work done by the wall is zero since there was no displacement of the wall, that is d = 0.
This relationship was first published by Sir Issac Newton. His law of universal gravitation says that the force (F) of gravitational attraction between two objects with Mass1 and Mass2 at distance D is: F = G(mass1*mass2)/D squared