Chapter 4, Problem 79A

a.

To determine

Puck’s acceleration.

Answer to Problem 79A

Acceleration of puck is $48{\text{ m/sec}}^2$ .

Explanation of Solution

Given:

Mass of the puck $m=0.25\text{ kg}$

Force applied $F=12\text{ N}$

Time for which force is applied $t=0.9\text{ sec}$

Formula used:

The force is given by,

  $F=ma$

Where,

m is mass

a is acceleration.

Calculation:

Substitute the value of F and m.

  $\begin{array}{c}12=0.25\times a\\ a=\frac{12}{0.25}\\ =48{\text{ m/sec}}^2\end{array}$

Conclusion:

Therefore, acceleration of puck is $48{\text{ m/sec}}^2$ .

b.

To determine

Puck’s final velocity.

Answer to Problem 79A

Final velocity of puck is 43.2 m/sec.

Explanation of Solution

Given :

Mass of the puck $m=0.25\text{ kg}$

Force applied $F=12\text{ N}$

Time for which force is applied $t=0.9\text{ sec}$

Acceleration of puck is $a=48{\text{ m/sec}}^2$

Formula used :

According to first equation of motion,

  $v=u+at$

Where,

u is the initial velocity.

v is the final velocity.

t is time.

a is acceleration.

Calculation:

Initial velocity of puck $u=0\text{ m/sec}$

Therefore,

  $\begin{array}{c}v=0+48\times 0.9\\ =0+43.2\\ =43.2\text{ m/sec}\end{array}$

Conclusion:

Therefore, final velocity of puck is 43.2 m/sec.