A block of mass $10$ kg, moving in the $x\text-$direction with a constant speed of $10$ ms^-1, is subjected to a retarding force $F=0.1x$ J/m during its travel from $x =20$ m to $30$ m. Its final kinetic energy will be:

A body of mass m dropped from a height h reaches the ground with a speed of 1.4$\sqrt{\mathrm{gh}}$. The work done by air drag is:

1. –0.2mgh 

2. –0.02mgh

3. –0.04mgh 

4. mgh

A force of 5 N making an angle $\theta$ with the horizontal acting on an object displaces it by 0.4 m along the horizontal direction. If the object gains kinetic energy of 1 J then the component of the force is:

The energy required to accelerate a car from rest to 30 m/s is E. The energy required to accelerate the car from 30 m/s to 60 m/s will be:

According to the work-energy theorem, the change in kinetic energy of a body is equal to work done by:

1.  Non-conservative force on the particle

2.  Conservative force on the particle

3.  External force on the particle

4.  All the forces on the particle

A block is carried slowly up an inclined plane. If $W_f$ is work done by the friction, $W_N$ is work done by the reaction force, $W_g$ is work done by the gravitational force, and $W_{ex}$ is the work done by an external force, then choose the correct relation(s):
1. $W _N +   W _f   +   W _g   +   W _{ex}   =   0$
2. $W _N   =   0$
3. $W _f   +   W _{ex}   =    - W _g$
4. All of these

A particle of mass $10$ kg moves with a velocity of $10\sqrt{x}$ in SI units, where $x$ is displacement. The work done by the net force during the displacement of the particle from $x=4~\text{m}$ to $x= 9~\text{m}$ is:
1. $1250~\text{J}$
2. $1000~\text{J}$
3. $3500~\text{J}$
4. $2500~\text{J}$

A block is released from rest from a height of $h = 5 ~\text m.$ After traveling through the smooth curved surface, it moves on the rough horizontal surface through a length $l = 8 ~\text m$ and climbs onto the other smooth curved surface at a height $h'.$ If $μ = 0.5,$ then the height $h'$ is:

A man pushes a wall and fails to displace it. He does:
1. negative work
2. positive but not maximum work
3. no work at all
4. maximum work