CBSE Class 11science Physics Conservative Forces

plz elaborate by figure and step by step 1 no. ka question
 What are conservative and nonconservative forces. Give one example of each force.
 Why a coolie does no work when he moves on a level road while carrying a box on his head?
 Write four properties of conservative forces.
 Explain that gravitational force is a conservative force.
 Calculate the velocity of the bob of simple pendulum at its mean position if it is able to rise to vertical height of 20 cm. Take g = 9.8 m/s^{2}.
 Find the maximum compression in a spring of spring constant 800 N/m, if it is hit by a ball of 0.5 kg released from the height of 10 m. The ball initially followed a curved path and then move horizontally on a frictionless surface to meet the target.
 A ball at rest is dropped from a height of 10 m. It loses 25% of its kinetic energy in striking the ground. Find the height to which it bounces. Give the reason of loss of kinetic energy.
 A ball of mass 0.1 kg is thrown vertically up with a velocity of 10 m/s. At what height, will its kinetic energy be half its original value?
 250 joules were spent in lifting a 10 kg weight to a height of 2 m. Calculate the acceleration with which it was raised. (Take g = 10 m/s^{2})