Force vector is given as

now we need to find the magnitude of this force
as we know that



so here we will find the net force



so it is having magnitude as 35.2 N
'Gram', 'kilogram', and 'metric ton' are units of mass, not weight.
'Pound' can be either a unit of mass or of force. Most people
use it most of the time to mean weight.
M, mass=84 kg
height, h=3.9m
gravity, g= 9.8m/s2
W = F . d
F=force
d=Displacement
W=work done by force
Now by putting the values
F= m g (Acting downward )
d= h (Upward)
W= m g h ( work done against the force)
W= 84•9.8•3.9J
W= 3210.48
Therefore the answer will be 3210.48J.
C..............................
Answer:
Interchanging the poles of the magnet
Reversing the direction of the applied current
Explanation:
- The working of the electric motor is associated with Fleming's left-hand rule.
- It states that if a current-carrying conductor is placed inside a magnetic field, it experiences a force in the direction perpendicular to the direction of the electric current and magnetic field.
- These three physical quantities are placed in a mutually perpendicular direction.
- So, in order to reverse the direction of force, you have to either change the direction of the current or magnetic field.