A ball is dropped on to the floor from a height of $20 \mathrm{m}$. It rebounds to a height of $10 \mathrm{m}$. If the ball is in contact with the floor for $0.1$ seconds, what is the average acceleration during contact?

What would you conclude about the velocity-time graph of the cyclist from the given graph?

Statement $1$ : An object thrown vertically up with a velocity $u$ reaches the maximum height $h$ after $T$ seconds. At a time $2T$seconds, its velocity becomes zero.

Statement $2$ : An object, thrown vertically up with a velocity $u$ comes back to its initial position with the same magnitude of velocity but in the opposite direction.

The velocity-time graph of an object is shown in the figure. Identify the correct statement(s) regarding this graph.

i) This is a non-uniform velocity-time graph of the object.

ii) The velocity of the object is increasing at the same rate during OP and QR.

iii) The velocity of the object is decreasing at the same rate during PQ and RT.

A boy takes $5 \mathrm{s}$ to reach each point from A to B, B to C and C to D as shown in the diagram. If $AB=BC=CD=20 \mathrm{m}$, then which of the following is correct when the body reaches D from A through BC?

Two racing cars of masses $m_1, m_2$ are moving in circles of radii $r_1, r_2$ respectively. Their speeds are such that each makes a complete circle in the same length of time $T$. The ratio of angular speed of the first car to the second car is :