Motion in a Straight Line · Question 8

A horizontal bridge is built across a river. A student standing on the bridge throws a small ball vertically upwards with a velocity 4 m s-1. The ball strikes the water surface after 4 s. The height of bridge above water surface is (Take g = 10 m s-2)

1. 60 m
2. 64 m
3. 68 m
4. 56 m

A bullet from a gun is fired on a rectangular wooden block with velocity u. When bullet travels 24 cm through the block along its length horizontally, velocity of bullet becomes u3. Then it further penetrates into the block in the same direction before coming to rest exactly at the other end of the block. The total length of the block is :

1. 24 cm
2. 28 cm
3. 30 cm
4. 27 cm

The ratio of the distances travelled by a freely falling body in the 1st, 2nd, 3rd and 4th second

1. 1 : 2 : 3 : 4
2. 1 : 4 : 9 : 16
3. 1 : 3 : 5 : 7
4. 1 : 1 : 1 : 1

The displacement-time graphs of two moving particles make angles of 30 and 45 with the x-axis as shown in the figure. The ratio of their respective velocity is [figure]

1. 3 : 1
2. 1 : 1
3. 1 : 2
4. 1 : 3

The position-time (x - t) graph for positive acceleration is

1. [figure]
2. [figure]
3. [figure]
4. [figure]

A small block slides down on a smooth inclined plane, starting from rest at time t = 0. Let Sn be the distance travelled by the block in the interval t = n - 1 to t = n. Then the ratio SnSn+1 is :

1. 2n2n-1
2. 2n-12n
3. 2n-12n+1
4. 2n+12n-1

A ball is thrown vertically downward with a velocity of 20 m/s from the top of a tower. It hits the ground after some time with a velocity of 80 m/s. The height of the tower is : (g = 10 m/s2)

1. 340 m
2. 320 m
3. 300 m
4. 360 m

When an object is shot from the bottom of a long smooth inclined plane kept at an angle 60 with horizontal, it can travel a distance x1 along the plane. But when the inclination is decreased to 30 and the same object is shot with the same velocity, it can travel x2 distance. Then x1 : x2 will be :

1. 1 : 2
2. 2 : 1
3. 1 : 3
4. 1 : 2 3

A toy car with charge q moves on a frictionless horizontal plane surface under the influence of a uniform electric field E. Due to the force q E, its velocity increases from 0 to 6 m s-1 in one second duration. At that instant the direction of the field is reversed. The car continues to move for two more seconds under the influence of this field. The average velocity and the average speed of the toy car between 0 to 3 seconds are respectively

1. 2 m s-1, 4 m s-1
2. 1 m s-1, 3 m s-1
3. 1 m s-1, 3.5 m s-1
4. 1.5 m s-1, 3 m s-1

Preeti reached the metro station and found that the escalator was not working. She walked up the stationary escalator in time t1. On another day, if she remains stationary on the moving escalator, then the escalator takes her up in time t2. The time taken by her to walk up on the moving escalator will be

1. t1t2t2-t1
2. t1t2t2+t1
3. t1-t2
4. t1+t22