Given below are two statements: 
Assertion (A): If two particles move with uniform accelerations in different directions, then their relative velocity changes in direction. 
Reason (R): Since the acceleration are in different directions, there is a relative acceleration and hence the relative velocity changes. 
 
1. (A) is True but (R) is False.
2. (A) is False but (R) is True.
3. Both (A) and (R) are True and (R) is the correct explanation of (A).
4. Both (A) and (R) are True but (R) is not the correct explanation of (A).
Subtopic:  Relative Motion |
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A man drifting on a raft on a river observes a boat moving in the same direction at a relative speed which is \(3\) times the speed of the river's flow of \(3\) km/h. The boat overtakes him at a certain moment and reaches a point downstream after a time \(T_B\) while he reaches the same point after \(T_A=3 \) hr. Then, \(T_B= \)

1. \(1\) hr 2. \(\dfrac12\)hr
3. \(\dfrac23\) hr 4. \(\dfrac34\) hr
Subtopic:  Relative Motion |
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A particle moves around a circle with a speed of \(\pi~\text{m/s},\) while another moves back-and-forth along a diameter with a speed of \(1~\text{m/s}.\) The minimum possible relative velocity between them is (in magnitude):
1. zero
2. \((\pi-1)~\text{m/s}\)
3. \(\sqrt{\pi^2+1}~\text{m/s}\)
4. \(\sqrt{\pi^2-1}~\text{m/s}\)
Subtopic:  Relative Motion |
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A man walks in the rain, where the raindrops are falling vertically down at a constant speed of \(4~\text{m/s}\) relative to ground. Let the relative velocity of a droplet with respect to man be \(v_r\) and let it make an angle \(\theta_r\) with the vertical. Then:
1. \(v_r=4\cos\theta_r~\text{m/s}\)
2. \(v_r=4\sin\theta_r~\text{m/s}\)
3. \(v_r=4\sec\theta_r~\text{m/s}\)
4. \(v_r=4~\mathrm{cosec }\theta_r~\text{m/s}\)
Subtopic:  Relative Motion |
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Two particles \(A\), \(B\) are projected simultaneously from the base of a triangle \(ABC\). Particle \(A\) is projected from vertex \(A\) along \(AC,\) and particle \(B\) is projected from vertex \(B\) along \(BC\). Their respective velocities are \(v_A\) & \(v_B\) and they move with uniform velocities. For the particles to collide:
1. \(v_A~\text{cos}A=v_B~\text{cos}B\)
2. \(v_A~\text{sin}A=v_B~\text{sin}B\)
3. \(\dfrac{v_A}{\text{sin}A}=\dfrac{v_B}{\text{sin}B}\)
4. \(v_A~\text{tan}A=v_B~\text{tan}B\)
Subtopic:  Relative Motion |
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A man, swimming with a speed \(u_1,\) can cross a river fastest in a time, \(T\). His friend, who swims with a speed \(u_2,\) reaches the opposite bank in the same time when he swims at an angle of \(30^{\circ}\) with the bank. Then:
1. \(u_1=\dfrac{\sqrt3}{2}u_2\) 2. \(u_1=\dfrac{1}{2}u_2\)
3. \(u_1=\dfrac{1}{\sqrt2}u_2\) 4. \(u_1=\dfrac{1}{\sqrt3}u_2\)
Subtopic:  Relative Motion |
 58%
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A boat is rowed across a \(400~\text m\) wide river so that it can reach the opposite bank in a minimum of \(10\) minutes. No matter which direction the boat is rowed in, it cannot reach a point exactly opposite on the other bank, unless it is rowed at a slightly higher speed. The speed of flow of the river is:
1. \(2.4~\text{km/h}\) 2. \(4.8~\text{km/h}\)
3. \(2.4\sqrt2~\text{km/h}\) 4. \(\dfrac{2.4}{\sqrt2}~\text{km/h}\)
Subtopic:  Relative Motion |
 59%
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A boat, when rowed perpendicular to the flow of a \(500\) m wide river, reaches its opposite bank in \(10\) min. If the boat is rowed downstream at an angle of \(30^\circ\) with the flow, it will cross in:
1. \(10\) min 2. \(5\sqrt3\) min
3. \(20\) min 4. \(\dfrac{10}{\sqrt3}\) min
Subtopic:  Relative Motion |
 60%
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Raindrops fall from the sky making an angle of \(30^\circ\) with the vertical. If a man runs at \(2\) m/s, he finds that the drops fall vertically. If he were to run in the opposite direction with the same speed\(,\) the raindrops will fall with a vertical speed of:
1. \(2\) m/s 2. \(4\) m/s
3. \(2\sqrt3 \) m/s 4. \(4\sqrt3 \) m/s
Subtopic:  Relative Motion |
 63%
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Given below are two statements: 
Assertion (A): If the velocities of two particles are perpendicular to each other, then their separation must be increasing with time.
Reason (R): The relative velocity between the two particles is higher in magnitude than either of them.
 
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.
Subtopic:  Relative Motion |
 52%

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