NEET Practice Questions (MCQs) with Answers & Solutions

Power = Work/ Time. 

Work = Force x displacement 

So, now Power = Force x displacement / Time. 

But displacement / Time = velocity 

According to the question, Force is F and V is velocity so, 

Power = F x v

But power is a scalar quantity so, we have dot product for power so...... 

Power = Fv or F.v

Power of gun = Total K.E.of fired bullet /time = $ n \times {1 \over 2 } mv^2 /t $

Work done by forces = 0 ;W = p/t

$ { 1 \over 2} mv^2 = kt $ ( K,constant t ) , $ v = \sqrt { 2k \over m } t^{1/2} $, $ dx = \sqrt { 2k \over m } t^{1/2} dt $ Take integration

The coefficient of restitution (e) measures the elasticity of a collision between two bodies. For a perfectly elastic collision, e is equal to 1. This means that there is no loss of kinetic energy in the collision, and the bodies rebound with the same relative velocity with which they approached each other.

when two balls at the same temperature collide some fraction of their kinetic energy appear in other forms of energy like heat energy,sound energy.hence neither temperature,not velocity or kinetic energy will remain conserved.the only quantity which will remain conserved is their momentum.

$ { v_2 \over v_1 } = \sqrt {h_2 \over h_1} $; i.e. fractional loss in velocity $ = 1 - { v_2 \over v_1} $

$ m_p v_p + m_Q v_Q = 0 $

mgh ' = 70% of mgh

Loss in K.E. = (initial K.E. - Final K.E.) of system = $ { 1 \over 2} m_1 u_1^2 + { 1 \over 2} m_2 u_2^2 - {1 \over 2( m_1 +m_2 )v^2 $