Question

The force $F$ which is applied to $1kg$ block initially at rest varies linearly with time as shown in the figure. Find velocity of the block at $t=4s$.

• A. $100m/s$
• B. $200m/s$
• C. $20m/s$
• D. $4m/s$

Answer 1

The correct option is B $200m/s$

From Graph: $F=25t$

using force balance: $F=ma$

$ma=25t$

$a=25t$

$\frac{dv}{dt}=25t$

$v={\int }_0^{4}25tdt$

$v=\frac{25}{2}\times 4^2$

$v=200m/s$