Answer:
Part a)

Part b)

Part c)

Part d)
Net force on a closed loop in uniform magnetic field is always ZERO

Explanation:
As we know that force on a current carrying wire is given as

now we have
Part a)
current in side 166 cm and magnetic field is parallel
so we have

here we know that L and B is parallel to each other so

Part b)
For 68.1 cm length wire we have

here we know that


so we have


Part c)
For 151 cm length wire we have

here we know that


so we have


Part d)
Net force on a closed loop in uniform magnetic field is always ZERO

A machine can never be 100% efficient because some work is always lost
due to the lack of materials or equipment that would convert work by 100%. It follows
the second law of entropy. The ideal engine is known as Carnot’s engine having
a 100% efficiency. So far, no engine has ever gotten to 100%.
Answer: 27 joules
Explanation:
Work is done when force is applied on the bench over a distance. it is measured in joules.
Workdone = force x distance
= 45 N x 0.6 metres
= 27 joules
Thus, 27 joules of work is done on the bench.