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8
MCQ (Multiple Correct Answer)

A graph of x versus t is shown in figure. Choose correct alternatives given below

A

The particle was released from rest at t = 0

B

At B, the acceleration a > 0

C

Average velocity for the motion between A and D is positive

D

The speed at D exceeds that at Ε

9
MCQ (Multiple Correct Answer)

For the one-dimensional motion, described by $x=t- \text{sin}t$

A

$x(t)>0$ for all $t>0$

B

$v(t)>0$ for all $t>0$

C

$a(t)>0$ for all $t>0$

D

$v(t)$ lies between $0$ and $2$

10
MCQ (Multiple Correct Answer)

A spring with one end attached to a mass and the other to a rigid support is stretched and released.

A

Magnitude of acceleration, when just released is maximum

B

Magnitude of acceleration, when at equilibrium position, is maximum

C

Speed is maximum when mass is at equilibrium position

D

Magnitude of displacement is always maximum whenever speed is minimum

11
MCQ (Multiple Correct Answer)

A ball is bouncing elastically with a speed 1 m/s between walls of a railway compartment of size 10 m in a direction perpendicular to walls. The train is moving at a constant velocity of 10 m/s parallel to the direction of motion of the ball. As seen from the ground:

A

The direction of motion of the ball changes every 10 s.

B

Speed of ball changes every 10 s.

C

Average speed of ball over any 20 s interval is fixed.

D

The acceleration of ball is the same as from the train.

12
Subjective

Refer to the graph in figure. Match the following:

GraphCharacteristics
(a)(i) has v > 0 and a < 0 throughout
(b)(ii) has x > 0 throughout and has a point with v = 0 and a point with a = 0
(c)(iii) has a point with zero displacement for t > 0
(d)(iv) has v < 0 and a > 0
A
B
C
D
Explanation

We have to analyze slope of each curve i.e., $\frac{dx}{dt}$. For peak points $\frac{dx}{dt}$ will be zero as x is maximum at peak points.

For graph (a), there is a point (B) for which displacement is zero. So, a matches with (iii)

In graph (b), x is positive (> 0) throughout and at point $B_1$, $v = \frac{dx}{dt}$ = 0. since, at point of curvature changes a = 0, So b matches with (ii)

In graph (c), slope $V = \frac{dx}{dt}$ is negative hence, velocity will be negative. so matches with (iv)

In graph (d), as slope $V = \frac{dx}{dt}$ is positive hence, V > 0

Hence, d matches with (i)