The $x{\rm{ \;and \;}}y$ coordinates of the particle at any time are $x = 5t - 2{t^2}{\rm{ \;and\; }}y = 10t$ respectively, where $x{\rm{ \;and\; }}y$ are in meters and $t$ in seconds. The acceleration of the particle at $t = 2s$ is

A particle moves with a constant speed v in a horizontal circular path. The change in its velocity on covering ${90^0}$ will be

A particle moves in a plane with position given by $x = 7t - 3t^3$ and $y = 8t^2$. What is the x-component of the particle's acceleration at $t = 1$ s?

The effective acceleration of a body, when thrown upwards with acceleration a will be

A particle moving with uniform acceleration along a straight line covers distances $S_1$ and $S_2$ in successive time intervals $t_1$ and $t_2$. Which equation correctly relates these quantities?

A particle starts its motion from rest under the action of a constant force. If the distance covered in first 10 seconds is ${S_1}$ and that covered in the first 20 seconds is ${S_2}$ , then

A car accelerates uniformly from rest to a speed of 20 m/s in 5 seconds. What is its acceleration?

A particle has initial velocity $\left( {2\hat i + 3\hat j} \right)$ and acceleration $\left( {0.3\hat i + 0.2\hat j} \right)$. The magnitude of velocity after 10 seconds will be

Percentage of total distance covered in 5th Second by a freely falling body is

A particle travelled ${\left( {\frac{3}{4}} \right)^{th}}$ of the circle of radius R in time t. The magnitude of the average velocity of the particle in this time interval is

A bus moves over a straight level road with a constant acceleration a. A body in the bus drops a ball outside. The acceleration of the ball with respect to the bus and the earth are respectively