A ball is projected at an angle with the horizontal. The angle of elevation of the ball when it is at the highest point is:
(1)
(2)
(3)
(4)
A particle is moving along a curve. Select the correct statement.
1. | If its speed is constant, then it has no acceleration. |
2. | If its speed is increasing, then the acceleration of the particle is along its direction of motion. |
3. | If its speed is decreasing, then the acceleration of the particle is opposite to its direction of motion. |
4. | If its speed is constant, its acceleration is perpendicular to its velocity. |
A man can row a boat with \(8\) km/h in still water. He is crossing a river of width \(8\) km, where the speed of water flow is \(4\) km/h. What direction should he head the boat to cross the river in the shortest time?
1. \(30^{\circ}\) with the current
2. \(60^{\circ}\) with the current
3. \(90^{\circ}\) with the current
4. \(120^{\circ}\) with the current
The horizontal range of a particle thrown from the ground is four times the maximum height. The angle of projection with the vertical is:
(1) 60°
(2) 30°
(3) 45°
(4) 90°
A particle is moving 30° north of east with speed 6 m/s. After 3 s the particle is found to be moving along north at the same speed. The magnitude of average acceleration in this interval of time is
(1) 1
(2) 6
(3) Zero
(4) 2
A particle is thrown with a velocity of 40 m/s. If it passes A and B as shown in the figure at time = 1 s and = 3 s. The value of h is:
(1) 15 m
(2) 10 m
(3) 30 m
(4) 20 m
At a certain moment, the angle between the velocity vector and the acceleration of a particle is greater than 90°. What can be inferred about its motion at that moment?
(1) It moves along a curve and its speed is decreasing.
(2) It moves along a straight line and accelerated.
(3) It moves along a curve and its speed is increasing.
(4) It moves along a straight line and it is decelerated.
To a stationary man, the rain is falling on his back with a velocity v at an angle with vertical. To make the rain-velocity perpendicular to the man, he:
(1) must move forward with a velocity vsin.
(2) must move forward with a velocity vtan.
(3) must move forward with a velocity vcos.
(4) should move in the backward direction.
A particle is thrown from the ground with a speed of 20 m/s at an angle 60° above the horizontal. Average velocity over its entire journey just before hitting the ground is:
(1) 10 m/s
(2) 20 m/s
(3) Zero
(4) 15 m/s
A person can throw a ball up to a maximum horizontal range of \(400~\text{m}\). The maximum height to which he can throw the ball is:
1. \(200~\text{m}\)
2. \(100~\text{m}\)
3. \(150~\text{m}\)
4. \(250~\text{m}\)