A person standing on the floor of an elevator drops a coin. The coin reaches the floor in time if the elevator is moving uniformly and time if the elevator is stationary. Then:
1. | \(t_1<t_2 \) or \(t_1>t_2 \) depending upon whether the lift is going up or down. |
2. | \(t_1<t_2 \) |
3. | \(t_1>t_2 \) |
4. | \(t_1=t_2 \) |
A person travelling in a straight line moves with a constant velocity \(v_1\) for a certain distance \(x\) and with a constant velocity \(v_2\) for the next equal distance. The average velocity \(v\) is given by the relation:
1. | \(\frac{1}{v} = \frac{1}{v_1}+\frac{1}{v_2}\) | 2. | \(\frac{2}{v} = \frac{1}{v_1}+\frac{1}{v_2}\) |
3. | \(\frac{v}{2} = \frac{v_1+v_2}{2}\) | 4. | \(v = \sqrt{v_1v_2}\) |
A particle moves along a path \(ABCD\) as shown in the figure. The magnitude of the displacement of the particle from \(A\) to \(D\) is:
1. m
2. \(10\) m
3. m
4. \(15\) m
The velocity of a particle moving along a straight line with constant acceleration 'a' reduces to of its initial velocity in time . The total time taken by the body till its velocity becomes zero is:
1.
2.
3.
4.
A boy falls from a building of height 320 m. After 5 seconds, superman jumps downward with initial speed u such that the boy can be saved. The minimum value of u is (assume g=10 )
1. | 95.1 m/s | 2. | 98.3 m/s |
3. | 91.6 m/s | 4. | 85.6 m/s |
The displacement x of a body having relation with time as , then distance covered by body in first two second is [where x is in metre and t is in second].
1. Zero
2. 6 m
3. 3 m
4. 9 m
The acceleration of particle for which the versus s graph is shown is:
1. - 8
2. 4
3. - 4
4. -16
Assertion: A body is momentarily at rest when it reverses the direction of motion.
Reason: A body cannot have acceleration if its velocity is zero at a given instant of time.
1. both Assertion and Reason are true and the reason is the correct explanation of the assertion.
2. both Assertion and Reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is a true statement but Reason is false.
4. both Assertion and Reason are false statements.
The position (x) of a particle moving along x-axis varies with time (t) as . The particle turns around at
1. t=1 s
2. t=2 s
3. t=3 s
4. t=4 s