An object of mass is not required for this problem

PHYSICS · Subjective · CBSE · Physics · Motion · Motion

Problem

An object of mass is not required for this problem. An ice-hockey puck slides on a horizontal frictionless surface with an initial speed

u

. A player hits the puck so that it experiences a uniform retardation of magnitude

a

until it comes to rest. (i) Derive an expression for the time

t_{\text{stop}}

taken by the puck to come to rest in terms of

u

and

a

. (ii) A puck is observed to slow down from

8\,\text{m/s}

to rest under a uniform retardation of

1.6\,\text{m/s}^2

. Using your result from part (i), calculate the time taken to stop. (iii) Immediately after coming to rest, the same retardation

1.6\,\text{m/s}^2

continues to act for a further

2\,\text{s}

in the same direction as before. Find the velocity of the puck at the end of this additional

2\,\text{s}

and state its direction with respect to the initial motion.