The motion of a particle along a straight line is described by equation $x = 8 + 12t - t^3$ where $x$ is in metre and $t$ in second. The retardation of the particle when its velocity becomes zero is...........$m/s^2$
$24$
$0$
$6$
$12$
Draw $x \to t$ graph for zero acceleration.
Consider the acceleration, velocity and displacement of a tennis ball as it falls to the ground and bounces back. Directions of which of these changes in the process
colum $I$ | colum $II$ |
$(A)$ Constant positive acceleration | $(p)$ Speed may increase |
$(B)$ Constant negative acceleration | $(q)$ Speed may decrease |
$(C)$ Constant displacement | $(r)$ Speed is zero |
$(D)$ Constant slope of $a-t$ graph | $(s)$ Speed must increase |