Question 1 :
Choose the correct statements. The coefficient of static friction depends on<br/>(1) the material of the bodies in contact.<br/>(2) quality of machining of the surface in contact.<br/>(3) presence of foreign matter between the surface.<br/>(4) area of the surfaces in contact.

Question 2 :
A marble block of mass $2kg$ lying on ice when given a velocity of $6m/s$ is stopped by friction in $10s$, then the coefficient of friction is (take g=$10 ms^{-2}$)

Question 3 :
A car has to move on a level turn of radius $45m$. If the coefficient of static friction between the tyre and the road is $\mu_s = 2.0$, find the maximum speed the car can take without skidding.

Question 4 :
A block of weight $100$ $N$ is lying on a rough horizontal surface. If coefficient of friction $\cfrac{1}{\sqrt{3}}$. The least possible force that can move the block is

Question 6 :
A {tex} 600 \mathrm { kg } {/tex} rocket is set for a vertical firing. If the exhaust speed is {tex} 1000 \mathrm { ms } ^ { - 1 } , {/tex} the mass of the gas ejected per second to supply the thrust needed to overcome the weight of rocket is

Question 7 :
The coefficient of friction between the tryes and the road is 0.25. the maximum speed with which a car can be driven round a curve of radius 40 m without skidding is (assume g= 10$ms^{-2}$)

Question 8 :
A stone is dropped from a height {tex} h . {/tex} It hits the ground with a certain momentum {tex} P {/tex}. If the same stone is dropped from a height {tex} 100 \% {/tex} more than the previous height, the momentum when it hits the ground will change by:

Question 9 :
Five persons {tex} A , B , C , D {/tex} and {tex} E {/tex} are pulling a cart of mass {tex} 100 \mathrm { kg } {/tex} on a smooth surface and cart is moving with acceleration {tex} 3 \mathrm { m } / \mathrm { s } ^ { 2 } {/tex} in east direction. When person {tex} A {/tex} stops pulling, it moves with acceleration {tex} 1 \mathrm { m } / \mathrm { s } ^ { 2 } {/tex} in the west direction. When person {tex} B {/tex} stops pulling, it moves with acceleration {tex} 24 \mathrm { m } / \mathrm { s } ^ { 2 } {/tex} in the north direction. The magnitude of acceleration of the cart when only {tex} A {/tex} and {tex} B {/tex} pull the cart keeping their directions same as the old directions, is

Question 10 :
The force required to stop a car of mass {tex} 800 \mathrm { kg } {/tex}, moving at a speed of {tex} 20 \mathrm { ms } ^ { - 1 } {/tex} over a distance of {tex} 25 \mathrm { m } {/tex} in {tex} 2.5 \mathrm { sec } {/tex} is