List of top Physics Questions on Work Power and Energy

A block of mass 1 kg, moving along x with speed \( v_i = 10 \) m/s enters a rough region ranging from \( x = 0.1 \) m to \( x = 1.9 \) m. The retarding force acting on the block in this range is \( F_r = -kx \) N, with \( k = 10 \) N/m. Then the final speed of the block as it crosses this rough region is
A block of mass 25 kg is pulled along a horizontal surface by a force at an angle $ 45^\circ $ with the horizontal. The friction coefficient between the block and the surface is 0.25. The displacement of 5 m of the block is:
Which one of the following forces cannot be expressed in terms of potential energy?
A body of mass 50 g is projected vertically upwards from the ground. If the kinetic energy of the body at a height of 32 m is 100% more than its potential energy, then the height at which the potential energy of the body becomes 60% of its kinetic energy is
A bullet of mass $m$ moving with a velocity $u$ gets embedded in a block of mass $M$ initially at rest. If $\mu$ is the coefficient of friction between the block and the ground, then the displacement of the block due to the impact is:
A body of mass 10 kg is moving with a velocity of 20 m/s. What is the kinetic energy of the body?
Energy is not carried by
A spring has a spring constant \( k \). When the spring is stretched through 1 cm, the potential energy is \( U \). What will be the potential energy if it is stretched by 4 cm?
If a force of \( (6x^2 - 4x) \, \text{N} \) acts on a body of mass 10 kg, then the work to be done by the force in displacing the body from \( x = 2 \, \text{m} \) to \( x = 4 \, \text{m} \) is
A force \( F \) is applied on a body of mass \( m \) so that the body starts moving from rest. The power delivered by the force at time \( t \) is proportional to:
A body is moving along a straight line under the influence of a constant power source. If the relation between the displacement (s) of the body and time (t) is \(s \propto t^x\), then \(x =\)
A train of mass \(10^6 \, \text{kg}\) is moving at a constant speed of \(108 \, \text{km/h}\). If the frictional force acting on it is \(0.5 \, \text{N per 100 kg}\), then the power of the train is
A simple pendulum of length 1m is released from horizontal position. If 20% its initial energy is lost due to air resistance in reaching the mean position, then the speed of the bob of the pendulum at mean position is (Acceleration due to gravity = 10 m s\textsuperscript{-2})
The work done to take a body of mass 100 kg to the top of a building of height 20 m is (Acceleration due to gravity = 10 m s\textsuperscript{-2})
A bomb of mass 12 kg at rest explodes into two pieces of masses 4 kg and 8 kg. If the velocity of 8 kg mass is \( 6\,{ms}^{-1} \), then the kinetic energy of 4 kg mass is
A body is dropped freely from a height of 8 m from the ground. If the coefficient of restitution between the body and the ground is 0.5, then the maximum height reached by the body after second impact with the ground is
A force of 10 N acts on a 2 kg object initially at rest, moving it 8 m along a straight line. What is the work done by the force? Assume the force is parallel to the displacement.
A particle of mass m moves on a straight line with its velocity increasing with distance according to the equation \( v = \alpha \sqrt{x} \), where \(\alpha\) is a constant. The total work done by all the forces applied on the particle during its displacement from \( x = 0 \) to \( x = d \), will be:
A machine with efficiency \( \frac{2}{3} \) used 12 J of energy in lifting a 2 kg block through a certain height and it is allowed to fall through the same. The velocity while it reaches the ground is:
A ball falls freely from rest on to a hard horizontal floor and repeatedly bounces. If the velocity of the ball just before the first bounce is 7 m/s and the coefficient of restitution is 0.75, the total distance travelled by the ball before it comes to rest (acceleration due to gravity = 10 ms\(^{-2}\)) is

The acceleration of a particle which moves along the positive \( x \)-axis varies with its position as shown in the figure. If the velocity of the particle is \( 0.8 \, \text{m/s} \) at \( x = 0 \), then its velocity at \( x = 1.4 \, \text{m} \) is:

A spring of \( 5 \times 10^3 \) Nm\(^{-1} \) spring constant is stretched initially by 10 cm from the unstretched position. The work required to stretch it further by another 10 cm is
The average power generated by a 90 kg mountain climber who climbs a summit of height 600 m in 90 minutes is (Acceleration due to gravity \( g = 10 \) m/s\(^2\)):

A force of \( (6x^2 - 4x + 3) \, \text{N} \) acts on a body of mass 0.75 kg and displaces it from \( x = 5 \, \text{m} \) to \( x = 2 \, \text{m} \). The work done by the force is

In an inelastic collision, after collision the kinetic energy