Answer:

Explanation:
The net force exerted on the mass is the sum of tension force and the external force of gravity.

is the tension force.
is the force of gravity.

where
is the rope's radius from the fixed point.
From the net force equation above:

Hence the tension force is 6.046N
Answer:
The torque is 0.31 Nm.
Explanation:
Electrical energy, E = 8400 J
time, t = 1 min
Angular speed, w = 2900 rpm = 303.53 rad/s
efficiency = 2/3 of input power
The toque is given by

Answer:
a) 2 m/s
b) i) 
ii) 
Explanation:
The function for distance is 
We know that:
Velocity = 
Acceleration = 
To find speed at time t = 0, we derivate the distance function:

Substitute t = 0 in velocity function:

Velocity at t = 0 will be 2 m/s.
To find the function for Kinetic Energy of the box at any time, t.

We know that 

