Answer:


Explanation:
k = Coulomb constant = 
Q = Charge
r = Distance = 8 cm
R = Radius = 4 cm
Electric field is given by

Volume charge density is given by

The volume charge density for the sphere is 

The magnitude of the electric field is 
Distance is the total length covered = 2m + 3m = 5m
Displacement is his distance from original position.
Displacement = 2m + (-3)m. Representing the 3m walked back as -3.
Displacement = 2m - 3m = -1m.
So his displacement is 1m behind his original starting point.
Answer:
B. 
Explanation:
Assuming we are dealing with a perfect gas, we should use the perfect gas equation:

With T the temperature, V the volume, P the pressure, R the perfect gas constant and n the number of mol, we are going to use the subscripts i for the initial state when the gas has 20 cubic inches of volume and absolute pressure of 5 psi, and final state when the gas reaches 10 psi, so we have two equations:
(1)
(2)
Assuming the temperature and the number of moles remain constant (number of moles remain constant if we don't have a leak of gas) we should equate equations (1) and (2) because
,
and R is an universal constant:
, solving for 


Answer:
Part a)

Direction of force is along the motion of charge
Part b)

direction of electric field is along the direction of motion
Explanation:
Part a)
As we know that the change in electric potential energy is equal to the work done by electric field


now from the equation of work done we know that



Direction of force is along the motion of charge
Part b)
As we know the relation between electrostatic force and electric field given as



direction of electric field is along the direction of motion