Download App

3.2 , motion in plane — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics3.2 , motion in plane1 Mark
MCQ
A projectile is fired with a speed $u$ at an angle $\theta$ with the horizontal. Its speed when its direction of motion makes an angle ‘$\alpha $’ with the horizontal is
  • A
    $u\,\, sec\theta \,\,cos\alpha$
  • B
    $u\,\, sec\theta\,\, sin\alpha$
  • ✓
    $u \,\,cos\theta \,\,sec\alpha$
  • D
    $u\,\, sin \theta \,\,sec\alpha$
✓

Answer

Correct option: C.
$u \,\,cos\theta \,\,sec\alpha$
c
Horizontal component of velocity $=v_{x}=u \cos \theta$

 vertical component of velocity $v_{y}=u \sin \theta-g t$

angle of velocity with horizontal $=\alpha$

$\tan a=\frac{v_{y}}{v_{x}}=\frac{(u \sin \theta-g t)}{(4 \cos \theta)}$

$t=\frac{u(\sin \theta-\cos \theta \tan \alpha)}{g}$

$v_{y}=u \cos \theta \tan \alpha$

$v_{x}=u \cos \theta$

So the speed of the projectile $=\sqrt{\left(\left(v_{x}\right)^{2}+\left(v_{y}\right)^{2}\right)}$

 $=u \cos \theta \sec \alpha$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from 3.2 , motion in plane→3.2 , motion in plane — all question types→Physics STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

A small drop of water falls from rest through a large height $h$ in air; the final velocity is ................
→
Sound waves of wavelength greater than that of audible sound are called
→
A moving particle of mass $m,$ makes a head on elastic collision with another particle of mass $2\,m,$ which is initially at rest. The percentage loss in energy of the colliding particle on collision, is close to .................. $\%$
→
A hanging mass $M$ is connected to a four times bigger mass by using a string-pulley arrangement. as shown in the figure. The bigger mass is placed on a horizontal ice-slab and being pulled by $2\,Mg$ force. In this situation. tension in the string is $\frac{x}{5}$ $Mg$ for $x =$ Neglect mass of the string and friction of the block (bigger mass) with ice slab. (Given $g=$ acceleration due to gravity)
→
A disc is given angular velocity ${\omega _0}$ as shown in figure and kept on an inclined plane of inclination $\theta $ having coefficient of friction $\mu$ = $tan \theta $ . The initial acceleration of centre of mass is $a$ and angular acceleration $\alpha $ , then
→
Two identical plates of different metals are joined to form a single plate whose thickness is double the thickness of each plate. If the coefficients of conductivity of each plate are $2$ and $3$ respectively, then the conductivity of composite plate will be
→
A ping-pong ball of mass $m$ is floating in air by a jet of water emerging out of a nozzle. If the water strikes the ping-pong ball with a speed $v$ and just after collision water falls dead, the rate of flow (in $kg/s$) of water in the nozzle is equal to
→
Two cylinders $A$ and $B$ fitted with pistons contain equal amounts of an ideal diatomic gas at $300 K$ . The piston of $A$ is free to move while that of $B$  is held fixed. The same amount of heat is given to the gas in each cylinder. If the rise in temperature of the gas in $A$ is $30 K$ , then the rise in temperature of the gas in $B$ is ..... $K$
→
The velocity of projection of a body is increased by $2 \% .$ Other factors remaining unchanged, what will be the percentage change in the maximum height attained ? (in $\%$)
→
If the metal bob of a simple pendulum is replaced by a wooden bob, then its time period will
→