Q. No.A ball of mass 0.5 kg moving with a velocity of 2 m/sec strikes a wall normally and bounces back with the same speed. If the time of contact between the ball and the wall is one millisecond, the average force exerted by the wall on the ball is:
(1) 2000 N
(2) 1000 N
(3) 5000 N
(4) 125 N
A particle moves in the \(XY\text-\)plane under the action of a force \(F\) such that the components of its linear momentum \(p\) at any time \(t\) are \(p_x = 2 \cos t\), \(p_y = 2 \sin t\). The angle between \(F\) and \(p\) at time \(t\) will be:
| 1. | \(90^{\circ}\) | 2. | \(0^{\circ}\) |
| 3. | \(180^{\circ}\) | 4. | \(30^{\circ}\) |
1. \(\frac{-2\alpha v^2}{M}\)
2. \(\frac{-\alpha v^2}{M}\)
3. \(\frac{\alpha v^2}{M}\)
4. \(-\alpha v^2\)
Swimming is possible on account of
(1) First law of motion
(2) Second law of motion
(3) Third law of motion
(4) Newton's law of gravitation
On a stationary sailboat, the air is blown at the sails from a fan attached to the boat. The boat will:
(1) remain stationary
(2) spin around
(3) move in a direction opposite to that in which air is blown
(4) move in the direction in which the air is blown
A man is standing at a spring platform. Reading of spring balance is 60 kg-wt. If a man jumps outside the platform, then reading of spring balance:
(1) first increases then decrease to zero.
(2) decreases.
(3) increases.
(4) remains same.
A body of mass 5 kg is suspended by a spring balance on a smooth inclined plane as shown in the figure. The spring balance measure:
(1) 50 N
(2) 25 N
(3) 500 N
(4) 10 N
A lift is going up. The total mass of lift and the passenger is \(1500\) kg. The variation in the speed of the lift is as given in the graph. The tension in the rope pulling the lift at \(t=11^{\text{th}}\) s will be:
1. \(17400\) N
2. \(14700\) N
3. \(12000\) N
4. zero
A player caught a cricket ball of mass 150 gm moving at a rate of 20 m/s. If the catching process be completed in 0.1 s, then the force of the blow exerted by the ball on the hands of the player is
(1) 0.3 N
(2) 30 N
(3) 300 N
(4) 3000 N
A rocket has a mass of 100 kg. 90% of this is fuel. It ejects fuel vapours at the rate of 1 kg/sec with a velocity of 500 m/sec relative to the rocket. It is supposed that the rocket is outside the gravitational field. The initial upthrust on the rocket when it just starts moving upwards is:
(1) Zero
(2) 500 N
(3) 1000 N
(4) 2000 N
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