Question

A body of $2kg$ has an initial speed $5m{s}^{-1}$ A force acts on it for some time in the direction of motion. The force time graph is shown in figure. The final speed of the body is

• A. $9.25m{s}^{-1}$
• B. $5m{s}^{-1}$
• C. $14.25m{s}^{-1}$
• D. $4.25m{s}^{-1}$

Answer 1

Answer: (C)

Impulse = Change in momentum $=m(v_2-v_1)\dots (i)$

Again impulse = Area between the graph and time axis

$=\frac{1}{2}\times 2\times 4+2\times 4+\frac{1}{2}(4+2.5)\times 0.5+2\times 2.5$

$=4+8+1.625+5=18.625\dots (ii)$

From (i) and (ii), $m(v_2-v_1)=18.625$

$\Rightarrow v_2=\frac{18.625}{m}+v_1=\frac{18.625}{2}+5$

$=14.25m/s$