If gravity is the ONLY force acting on an object, that's when we say the object is in "<em>free fall</em>".
Answer:
(A) Torque required is 21.205 N-m
(b) Wok done will be equal to 1199.1286 j
Explanation:
We have given moment of inertia 
Wheel deaccelerate from 135 rpm to 0 rpm
135 rpm = 
Time t = 8 sec
So angular speed
and 
Angular acceleration is given by 
Torque is given by torque 

Work done to accelerate the vehicle is


Answer:
3) D: 31 m/s
4) D: 84.84 metres
Explanation:
3) Initial velocity along the x-axis is;
v_x = v_o•cos θ
Initial velocity along the y-axis is;
v_y = v_o•sin θ
Plugging in the relevant values, we have;
v_x = 31 cos 60
v_x = 31 × 0.5
v_x = 15.5 m/s
Similarly,
v_y = 31 sin 60
v_y = 31 × 0.8660
v_y = 26.85 m/s
Thus, magnitude of the initial velocity is;
v = √(15.5² + 26.85²)
v ≈ 31 m/s
4) Formula for horizontal range is;
R = (v² sin 2θ)/g
R = (31² × sin (2 × 60))/9.81
R = 84.84 m
Radiation transfers heat by electromagnetic waves