2014
Q51
Advance
ARCHIVE: JEE MAIN
MCQ
From a tower of height $H$ , a particle is thrown vertically upwards with a speed $u$ . The time taken by the particle, to hit the ground, is $n$ times that taken by it to reach the highest point of its path. The relation between $H$ , $u$ and $n$ is
A.
$gH = (n - 2)u^2$
B.
$2gH = n^2 u^2$
C.
$gH = (n - 2)^2 u^2$
D.
$2gH = nu^2 (n - 2)$
JEE (Advanced) 2014
Q52
Advance
ARCHIVE: JEE ADVANCED
Numerical
A rocket is moving in a gravity free space with a constant acceleration of $2\mathrm{ms}^{-2}$ along $+x$ direction (shown in figure). The length of a chamber inside the rocket is $4\mathrm{m}$ . A ball is thrown from the left end of the chamber in $+x$ direction with a speed of $0.3\mathrm{ms}^{-1}$ relative to the rocket. At the same time, another ball is thrown in $-x$ direction with a speed of $0.2\mathrm{ms}^{-1}$ from its right end relative to the rocket. The time in seconds when the two balls hit each.
Correct Answer: 2 or 8
Explanation:
Let us consider motion of two balls with respect to rocket.

Motion of ball A relative to rocket
Maximum distance of ball A from left wall is
$S _ {A} = \frac {u ^ {2}}{2 a} = \frac {0 . 3 \times 0 . 3}{2 \times 2} = \frac {0 . 0 9}{4} \approx 0. 0 2 \mathrm{m} \left\{\because 0 = u ^ {2} - 2 a S \right\}$
So, collision of two balls will take place very near to left wall.
Motion of ball B relative to rocket
$\begin{array}{c c} \longleftarrow 2 \mathrm{ms} ^ {- 2} \\ \longleftarrow \circ & \longleftarrow + \mathrm{ve} \\ 0. 2 \mathrm{ms} ^ {- 1} & - \mathrm{ve} \end{array}$
$S = u t + \frac {1}{2} a t ^ {2}$
$\Rightarrow - 4 = - 0. 2 t - \left(\frac {1}{2}\right) 2 t ^ {2}$
Solving this equation, we get
$t = 1. 9 \mathrm{s}$
Nearest Integer = 2 s

Motion of ball A relative to rocket
Maximum distance of ball A from left wall is
$S _ {A} = \frac {u ^ {2}}{2 a} = \frac {0 . 3 \times 0 . 3}{2 \times 2} = \frac {0 . 0 9}{4} \approx 0. 0 2 \mathrm{m} \left\{\because 0 = u ^ {2} - 2 a S \right\}$
So, collision of two balls will take place very near to left wall.
Motion of ball B relative to rocket
$\begin{array}{c c} \longleftarrow 2 \mathrm{ms} ^ {- 2} \\ \longleftarrow \circ & \longleftarrow + \mathrm{ve} \\ 0. 2 \mathrm{ms} ^ {- 1} & - \mathrm{ve} \end{array}$
$S = u t + \frac {1}{2} a t ^ {2}$
$\Rightarrow - 4 = - 0. 2 t - \left(\frac {1}{2}\right) 2 t ^ {2}$
Solving this equation, we get
$t = 1. 9 \mathrm{s}$
Nearest Integer = 2 s
JEE (Advanced) 2014
Q53
Advance
ARCHIVE: JEE ADVANCED
Numerical
Airplanes A and B are flying with constant velocity in the same vertical plane at angles $30^{\circ}$ and $60^{\circ}$ with respect to the horizontal respectively as shown in figure. The speed of A is $100\sqrt{3}$ ms $^{-1}$ . At time t=0 s, an observer in A finds B at a distance of 500 m. This observer sees B moving with a constant velocity perpendicular to the line of motion of A. If at $t=t_{0}$ , A just escapes being hit by B, $t_{0}$ in seconds is
Correct Answer: 5
Explanation:
Relative velocity of B with respect to A is perpendicular to line PA. Therefore, along the line PA, velocity components of A and B should be same.
JEE-Main 2013
Q54
Allen
JEE-Main PYQs
MCQ
A projectile is given an initial velocity of $(\hat{t} + 2\hat{j})$ m/s, where $\hat{t}$ is along the ground and $\hat{j}$ is along the vertical. If $g = 10 \, m/s^{2}$ , the equation of its trajectory is :
A.
$y = x - 5x^{2}$
B.
$y = 2x - 5x^{2}$
C.
$4y = 2x - 5x^{2}$
D.
$4y = 2x - 25x^{2}$
2011
Q55
Advance
ARCHIVE: JEE MAIN
MCQ
An object moving with a speed of $6.25 \, ms^{-1}$ , is decelerated at a rate given by $\frac{dv}{dt} = -2.5\sqrt{v}$ , where v is the instantaneous speed. The time taken by the object, to come to rest, would be
A.
1 s
B.
2 s
C.
4 s
D.
8 s
2010
Q56
Advance
ARCHIVE: JEE MAIN
MCQ
A particle is moving with velocity $\vec{v} = K(y\hat{i} + x\hat{j})$ where $K$ is a constant. The general equation for its path is
A.
$y^{2} = x^{2} + \text{constant}$
B.
$y = x^{2} + \text{constant}$
C.
$y^{2} = x + \text{constant}$
D.
$xy = \text{constant}$
2009
Q57
Advance
ARCHIVE: JEE MAIN
MCQ
A particle has an initial velocity $3\hat{i} + 4\hat{j}$ and an acceleration of $0.4\hat{i} + 0.3\hat{j}$ . Its speed after 10 s is
A.
10 units
B.
$7\sqrt{2}$ units
C.
7 units
D.
8.5 units
JEE (Advanced) 2008
Q58
Advance
ARCHIVE: JEE ADVANCED
MCQ
Statement-I: For an observer looking out through the window of a fast moving train, the nearby objects appear to move in the opposite direction to the train, while the distant objects appear to be stationary. Statement-II: If the observer and the object are moving at velocities $v_{1}$ and $v_{2}$ , respectively with reference to a laboratory frame, the velocity of the object with respect to the observer is $v_{2} - v_{1}$ .
A.
If both statements are TRUE and STATEMENT 2 is the correct explanation of STATEMENT 1.
B.
If both statements are TRUE but STATEMENT 2 is not the correct explanation of STATEMENT 1.
C.
If STATEMENT 1 is TRUE and STATEMENT 2 is FALSE.
D.
If STATEMENT 1 is FALSE but STATEMENT 2 is TRUE.
IIT-JEE 2005
Q59
Advance
ARCHIVE: JEE ADVANCED
MCQ
The given graph shows the variation of velocity with displacement. Which one of the graph given below correctly represents the variation of acceleration with displacement?
A.
B.
C.
D.
IIT-JEE 2004
Q60
Advance
ARCHIVE: JEE ADVANCED
MCQ
A small block slides without friction down an inclined plane starting from rest. Let $S_{n}$ be the distance travelled from time $t = n - 1$ to $t = n$ . Then $\frac{S_n}{S_{n+1}}$ is
A.
$\frac{2n - 1}{2n}$
B.
$\frac{2n + 1}{2n - 1}$
C.
$\frac{2n - 1}{2n + 1}$
D.
$\frac{2n}{2n + 1}$
IIT-JEE 2004
Q61
Advance
ARCHIVE: JEE ADVANCED
MCQ
A particle starts from rest. Its acceleration $(a)$ versus time $(t)$ is as shown in the figure. The maximum speed of the particle will be
A.
$110\mathrm{ms}^{-1}$
B.
$55\mathrm{ms}^{-1}$
C.
$550\mathrm{ms}^{-1}$
D.
$660\mathrm{ms}^{-1}$
CBSE PMT 2003
Basic Level
Q62
Errorless
Motion Under Gravity
MCQ
The acceleration due to gravity on the planet A is 9 times the acceleration due to gravity on planet B. A man jumps to a height of 2m on the surface of A. What is the height of jump by the same person on the planet B
A.
18m
B.
6m
C.
$\frac{2}{3}m$
D.
$\frac{2}{9}m$
CPMT 2003
Basic Level
Q63
Errorless
Motion Under Gravity
MCQ
Two balls are dropped from heights h and 2h respectively from the earth surface. The ratio of time of these balls to reach the earth is
A.
$1 : \sqrt{2}$
B.
$\sqrt{2} : 1$
C.
2 : 1
D.
1 : 4
MP PET 2002
Basic Level
Q64
Errorless
Speed and Velocity
MCQ
The ratio of the numerical values of the average velocity and average speed of a body is always
A.
Unity
B.
Unity or less
C.
Unity or more
D.
Less than unity
MP PMT 2002
Basic Level
Q65
Errorless
Motion Under Gravity
MCQ
A body falling from a high Minaret travels 40 meters in the last 2 seconds of its fall to ground. Height of Minaret in meters is (take $g = 10m / s^2$ )
A.
60
B.
45
C.
80
D.
50
Kerala PMT 2002
Basic Level
Q66
Errorless
Motion Under Gravity
MCQ
A cricket ball is thrown up with a speed of $19.6 \, ms^{-1}$ . The maximum height it can reach is
A.
9.8 m
B.
19.6 m
C.
29.4 m
D.
39.2 m
AIIMS 2002
Basic Level
Q67
Errorless
Motion Under Gravity
MCQ
Three different objects of masses $m_1, m_2$ and $m_3$ are allowed to fall from rest and from the same point 'O' along three different frictionless paths. The speeds of the three objects, on reaching the ground, will be in the ratio of
A.
$m_1: m_2: m_3$
B.
$m_1: 2m_2: 3m_3$
C.
$1: 1: 1$
D.
$\frac{1}{m_1}: \frac{1}{m_2}: \frac{1}{m_3}$
Kerala (Engg.) 2001
Basic Level
Q68
Errorless
Speed and Velocity
MCQ
A particle moves along a semicircle of radius 10m in 5 seconds. The velocity of the particle is
A.
$2\pi ms^{-1}$
B.
$4\pi ms^{-1}$
C.
$2 ms^{-1}$
D.
$4 ms^{-1}$
CBSE PMT 2001
Basic Level
Q69
Errorless
Speed and Velocity
MCQ
A 150 m long train is moving with a uniform velocity of 45 km/h. The time taken by the train to cross a bridge of length 850 meters is
A.
56 sec
B.
68 sec
C.
80 sec
D.
92 sec
MP PMT 2001
Basic Level
Q70
Errorless
Acceleration
MCQ
A particle moves along a straight line such that its displacement at any time t is given by $s = t^{3} - 3t^{2} + 2$ meter. The displacement when the acceleration becomes zero is
A.
0 meter
B.
2 meter
C.
3 meter
D.
- 2 meter
DCE 2001; AIIMS 2002
Advance Level
Q71
Errorless
Velocity Time Graph
MCQ
A particle starts from rest, accelerates at $2 \, m/s^{2}$ for 10s and then goes for constant speed for 30s and then decelerates at $4 \, m/s^{2}$ till it stops. What is the distance travelled by it
A.
750 m
B.
800 m
C.
700 m
D.
850 m
UPSEAT 2001
Basic Level
Q72
Errorless
Motion Under Gravity
MCQ
A particle when thrown, moves such that it passes from same height at 2 and 10s, the height is
A.
g
B.
2g
C.
5g
D.
8g
11-JEE 2000
Q73
Advance
ARCHIVE: JEE ADVANCED
MCQ
A ball is dropped vertically from a height $d$ above the ground. It hits the ground and bounces up vertically to a height $\frac{1}{2} d$ . Neglecting subsequent motion and air resistance, its velocity $v$ varies with the height $h$ above the ground as
A.
B.
C.
D.
DCE 2000
Basic Level
Q74
Errorless
Distance and Displacement
MCQ
A body moves 6 m north. 8 m east and 10 m vertically upwards, what is its resultant displacement from initial position
A.
$10\sqrt{2}m$
B.
10m
C.
$\frac{10}{\sqrt{2}}m$
D.
$10\times2m$
BHU 2000
Basic Level
Q75
Errorless
Acceleration
MCQ
A body is moving according to the equation $x = at + bt^{2} - ct^{3}$ where x = displacement and a, b and c are constants. The acceleration of the body is
A.
$a + 2bt$
B.
$2b + 6ct$
C.
$2b - 6ct$
D.
$3b - 6ct^{2}$


