NCERT Solutions

a railway carriage moving without jerks between two stations.

a monkey sitting on top of a man cycling smoothly on a circular track.

a spinning cricket ball that turns sharply on hitting the ground.

a tumbling beaker that has slipped off the edge of a table.

(A/B) lives closer to the school than (B/A)

(A/B) starts from the school earlier than (B/A)

(A/B) walks faster than (B/A)

A and B reach home at the (same/different) time

What is the direction of acceleration during the upward motion of the ball?

What are the velocity and acceleration of the ball at the highest point of its motion?

Choose the $x=0 \text{ m}$ and $t=0 \text{ s}$ to be the location and time of the ball at its highest point, vertically downward direction to be the positive direction of x-axis, and give the signs of position, velocity and acceleration of the ball during its upward, and downward motion.

To what height does the ball rise and after how long does the ball return to the player's hands? (Take $g = 9.8 \text{ m s}^{-2}$ and neglect air resistance).

with zero speed at an instant may have non-zero acceleration at that instant

with zero speed may have non-zero velocity,

with constant speed must have zero acceleration,

with positive value of acceleration must be speeding up.

magnitude of displacement (sometimes called distance) over an interval of time, and the total length of path covered by a particle over the same interval;

magnitude of average velocity over an interval of time, and the average speed over the same interval. [Average speed of a particle over an interval of time is defined as the total path length divided by the time interval]. Show in both (a) and (b) that the second quantity is either greater than or equal to the first. When is the equality sign true? [For simplicity, consider one-dimensional motion only].

magnitude of average velocity, and

average speed of the man over the interval of time (i) 0 to 30 min, (ii) 0 to 50 min, (iii) 0 to 40 min?