- Home
- Standard 11
- Physics
A car starts from rest and accelerates at $5 \,\mathrm{~m} / \mathrm{s}^{2}$. At $t=4 \mathrm{~s}$, a ball is dropped out of a window by a person sitting in the car. What is the velocity and acceleration of the ball at $\mathrm{t}=6\, \mathrm{~s}$ ?
(Take g $\left.=10\, \mathrm{~m} / \mathrm{s}^{2}\right)$
$20\, \mathrm{~m} / \mathrm{s}, 5 \,\mathrm{~m} / \mathrm{s}^{2}$
$20 \,\mathrm{~m} / \mathrm{s}, 0$
$20\, \sqrt{2} \mathrm{~m} / \mathrm{s}, 0$
$20 \,\sqrt{2} \mathrm{~m} / \mathrm{s}, 10\, \mathrm{~m} / \mathrm{s}^{2}$
Solution
$\mathrm{u}=0$
$\mathrm{a}=5$
$\mathrm{t}=4$
$V=u+a t$
$V=0+5 \times 4$
$V=20$
$\mathrm{V}_{\mathrm{x}}=20\, \mathrm{~m} / \mathrm{sec}$
$\mathrm{V}_{\mathrm{y}}=\mathrm{u}+\mathrm{ut}$
$=10 \times 2$
$\mathrm{~V}_{\mathrm{y}}=20\, \mathrm{~m} / \mathrm{sec}$
$\mathrm{V}=20 \sqrt{2}$
and $\mathrm{a}=10\, \mathrm{~m} / \mathrm{sec}^{2}$
