52 -- A car with mass $2\,\text{t}$ moves on a horizontal surface at a constant speed of $18\,\dfrac{\text{km}}{\text{h}}$ along a circular path with radius $20\,\text{m}$. How many Newtons is the centripetal force and which force provides it?

• [(1)] $2500$ -- kinetic friction force
• [(2)] $2500$ -- static friction force
• [(3)] $1250$ -- kinetic friction force
• [(4)] $1250$ -- static friction force

The minimum velocity (in $\mathrm{ms}^{-1}$) with which a car driver must traverse a flat curve of radius 150 m and coefficient of friction 0.6 to avoid skidding is
(1) 60
(2) 30
(3) 15
(4) 25

Consider a car moving on a straight road with a speed of $100 \mathrm{~m}/\mathrm{s}$. The distance at which car can be stopped is $[\mu_\mathrm{k} = 0.5]$
(1) 800 m
(2) 1000 m
(3) 100 m
(4) 400 m

A curve in a level road has a radius 75 m. The maximum speed of a car turning this curved road can be $30 \mathrm{~m~s}^{-1}$ without skidding. If radius of curved road is changed to 48 m and the coefficient of friction between the tyres and the road remains same, then maximum allowed speed would be $\_\_\_\_$ $\mathrm{m~s}^{-1}$.