Assertion (A): | The average and instantaneous velocities have the same value in a uniform motion. |
Reason (R): | In uniform motion, the velocity of an object increases uniformly. |
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. | Both (A) and (R) are false. |
A person sitting on the ground floor of a building notices through the window, of height \(1.5~\text{m}\), a ball dropped from the roof of the building crosses the window in \(0.1~\text{s}\). What is the velocity of the ball when it is at the topmost point of the window? \(\left(g = 10~\text{m/s}^2\right )\)
1. | \(15.5~\text{m/s}\) | 2. | \(14.5~\text{m/s}\) |
3. | \(4.5~\text{m/s}\) | 4. | \(20~\text{m/s}\) |
A stone is thrown vertically downwards with an initial velocity of \(40\) m/s from the top of a building. If it reaches the ground with a velocity of \(60\) m/s, then the height of the building is: (take \(g=10\) m/s2)
1. | \(120\) m | 2. | \(140\) m |
3. | \(80\) m | 4. | \(100\) m |
1. | maximum speed = \(24\) m/s; distance = \(480\) m |
2. | maximum speed = \(20\) m/s; distance = \(400\) m |
3. | maximum speed = \(9.0\) m/s; distance = \(200\) m |
4. | maximum speed = \(9.0\) m/s; distance = \(180\) m |
Assertion (A): | Two balls of different masses are thrown vertically upward with the same speed. They will pass through their point of projection in the downward direction with the same speed. |
Reason (R): | The maximum height and downward velocity attained at the point of projection are independent of the mass of the ball. |
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. | Both (A) and (R) are False. |
1. | \(10\) m/s | 2. | \(19.6\) m/s |
3. | \(29.2\) m/s | 4. | \(9.8\) m/s |
A person standing near the edge of the top of a building throws two balls \(A\) and \(B.\) The ball \(A\) is thrown vertically upward and \(B\) is thrown vertically downward with the same speed. The ball \(A\) hits the ground with a speed \(v_A\) and the ball \(B\) hits the ground with a speed \(v_B.\) We have:
1. | \(v_A>v_B\) |
2. | \(v_A<v_B\) |
3. | \(v_A=v_B\) |
4. | the relation between \(v_A\) and \(v_B\) depends on height of the building above the ground |