Question

A ball is thrown vertically upwards. Which of the following plots represents the speed-time graph of the ball during its flight if the air resistance is not ignored? (Assume that magnitude of resistive force is constant )

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

$v=u+at$
For upward motion,
$a=-\frac{mg+R}{m}$ (Here $R$ represesnts air resistance)
$a=-(g+\frac{R}{m})$
$\therefore v=u-(g+\frac{R}{m})t+u$
compare with $y=-mx+c$



for downward motion,
$a=\frac{mg-R}{m}$ or $a=g-\frac{R}{m}$
$v=0+(g-\frac{R}{m})t$
or $v=(g-\frac{R}{m})t$
compare with $y=mx$