Question

A body of mass $2$ kg starts with an initial velocity $5m/s$. If the body is acted upon by a time dependent force(F) as shown in figure, then work done on the body in $20$s is:

• A. $-875J$
• B. $875J$
• C. $600J$
• D. $-600J$

Answer 1

The correct option is A $-875J$

$M=2kg$

$u=om/s$

$v=5m/s$

$t=20s$

so,acceleration $=\frac{(v-u)}{t}=\frac{5}{20}=\frac{1}{5}m/s^2$ therefore,force$=2\times \frac{1}{5}=0.4N$

$s=\frac{1}{2}a{t}^2=\frac{1}{2}\times \frac{1}{5}\times 20\times 20=40m$

so,work=force x displacement$=0.4\times 40=16J$