You literally just put your fingers in your genitals? is this for a sex ed course...?
Answer:
Explanation:
Given
mass of spring 
extension in spring 
downward velocity 
Position in undamped free vibration is given by

where 
also 



it is given


substituting values we get







It must be a virtual image, because this is the only kind of image it can produce.
Explanation:
Momentum before = momentum after
m₁ u₁ + m₂ u₂ = m₁ v₁ + m₂ v₂
(65 kg) (0 m/s) + m (0 m/s) = (65 kg) (-3.5 m/s) + m (4 m/s)
m ≈ 57 kg
If the surface is rough then the average force needed to move the wooden block will be more as the friction between the surfaces will be more.
Hence, the least force will be required on the smoothest surface and the greatest force will be required for the roughest surface.
a) Hence, the order will be: B > D > A > C
b) When the surface is glued then the force of friction will increase. Hence, it will require more force to move the wooden block on the surface. Hence, the more required will be more than 105 N.