1
WB JEE 2023
MCQ (More than One Correct Answer)
+2
-0

A train is moving along the tracks at a constant speed u. A girl on the train throws a ball of mass m straight ahead along the direction of motion of the train with speed $$\mathrm{v}$$ with respect to herself. Then

A
Kinetic energy of the ball as measured by the girl on the train is $$\mathrm{mv}^{2} / 2$$.
B
Work done by the girl in throwing the ball is $$\mathrm{mv}^{2} / 2$$.
C
Work done by the train is mvu.
D
The gain in kinetic energy of the ball as measured by a person standing by the rail track is $$\mathrm{mv}^{2} / 2$$.
2
WB JEE 2022
MCQ (More than One Correct Answer)
+2
-0

A particle is moving in x-y plane according to $$\overrightarrow r = b\cos \omega t\widehat i + b\sin \omega t\widehat j$$, where $$\omega$$ is constant. Which of the following statement(s) is/are true?

A
$${E \over \omega }$$ is a constant where E is the total energy of the particle.
B
The trajectory of the particle in x-y plane is a circle.
C
In ax - ay plane, trajectory of the particle is an ellipse (ax, ay denotes the components of acceleration)
D
$$\overrightarrow a = {\omega ^2}\overrightarrow v$$
3
WB JEE 2021
MCQ (More than One Correct Answer)
+2
-0
The potential energy of a particle of mass 0.02 kg moving along X-axis is given by V = Ax (x $$-$$ 4) J, where x is in metre and A is a constant. Which of the following statements is/are correct?
A
The particle is acted upon by a constant force.
B
The particle executes simple harmonic motion.
C
The speed of the particle is maximum at x = 2 m.
D
The period of oscillation of the particle is $${\pi \over 5}sec$$.
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