Question

A $45kg$ child on a sled is pulled through $6.00m$ on a horizontal field of ice with minimal friction. A $60N$ force is applied horizontally.
If the child is initially at rest, how fast will he/she be going at the $6.00m$ mark?

• A. $0m/s$
• B. $2m/s$
• C. $4m/s$
• D. $16m/s$
• E. None of the above

Answer 1

The correct option is C $4m/s$

Given : $m=45$ kg $u=0$ m/s $S=6.00$ m

Horizontal force applied on the child $F=60$ N

Thus acceleration of the child $a=\frac{F}{m}=\frac{60}{45}=1.33$ $m/s^2$

Using $v^2-u^2=2aS$

$\therefore$ $v^2-0=2\times 1.33\times 6.00$ $⟹v=4$ $m/s$