A car of maas M is moving on a horizontal circular path of radius r. At an instant its speed is v and is increasing at a rate a.

Options

A. The acceleration of the car is towards the centre of the path
B. The magnitude of the frictional force on the car is greater than `(mv^(2))/r`
C. The friction coefficient between the ground and the is less than a/g.
D. The friction coefficient between the ground and the car is `mu=tan^(-1). (v^(2))/(rg)`

Answer

B

Explanation

`a_(t)=(dv)/(dt)=a`
friction force on car =`msqrt(((v^(2))/r)^(2)+a^(2))`
which is greater than `(mv^(2))/r`
`mu_("min")=(sqrt((v^(2)//r^(2))+a^(2)))/g`
therefore, it is not less than `a/g` for safe turn.