Which of the following is not a fundamental force in nature?

$A$ car of mass $500\, kg$ is driven with acceleration $1\, m/s^2$ along a straight level road against a constant external resistance of $1000\, N$. When the velocity is $5\, m/s$,the rate at which the engine is working is .............. $kW$.

Place a uniform meter scale horizontally on your extended index fingers with the left one at $0.00 \ cm$ and the right one at $90.00 \ cm$. When you attempt to move both fingers slowly towards the center,initially only the left finger slips with respect to the scale and the right finger does not. After some distance,the left finger stops and the right one starts slipping. Then the right finger stops at a distance $x_R$ from the center $(50.00 \ cm)$ of the scale and the left one starts slipping again. This happens because of the difference in the frictional forces on the two fingers. If the coefficients of static and dynamic friction between the fingers and the scale are $0.40$ and $0.32$,respectively,the value of $x_R$ (in $cm$) is:

$A$ force of $5\,N$ acts on a body of mass $5\,kg$ for $1\,s$ and gives it a momentum $p$ and kinetic energy $E$. If the same force accelerates the same body through $1\,m$,the momentum and energy attained by the body are $p'$ and $E'$ respectively. Which of the following relations is correct?

If the overbridge is concave instead of being convex,the thrust on the road at the lowest position will be

Which of the following is not a method of reducing friction?