Answer:
a) 1504.8 J
b) 991.76 J
c) 0J
d) 0J
Explanation:
(a) The work done by the force P on the box is given by the following formula:

P: applied force = 171N
x: distance in which the for P is applied = 8.80m
you replace the values of P and x and obtain:

(b) The work don by the friction force is:

μ = coefficient of kinetic friction = 0.250
M: mass of the box = 46.0kg
g: gravitational constant = 9.8 m/s^2

(c) The Normal force is

but this force does not do work on the box because the direction is perpendicular to the direction of the force P.

(d) the same as before:

Power = 
Delilah: 170J/30s = 5.66 W
Adam: 260J/20s = 13 W
Answer:

Explanation:
As we know that when charge particle is projected in perpendicular magnetic field then the radius of the charge particle is given as


now we have

since here radius of proton and electron will be same
so we will have


so we have

given that



so we have


Answer:
Can a room be gravitationally shielded? No, it can't.
Explanation:
the room cannot be gravitationally shielded because there is only one gravitational charge, in this case is mass. Mass can always be positive. the room can be electrically shielded because there are two type of charge, positive and negative charge than can cancel each other out.
Answer:
The potential energy when it reads 40 N is 
Explanation:
From the question we are told that
The lowest reading of the spring balance is 0 N and this is at 0 cm = 0 m
The height reading of the spring balance is 60 N and this is at 20 cm = 0.20 m
Generally the length corresponding to the reading of 40 N is mathematically represented as

=> 
Generally the potential energy is mathematically represented as

Here
So

=> 