A train is moving slowly on a straight track with a constant speed of 2 ms^-1. A passenger in that train starts walking at a steady speed of 2 ms^-1 to the back of the train in the opposite direction of the motion of the train. So to an observer standing on the platform directly in front of that passenger, the velocity of the passenger appears to be

• 4 ms^-1

• 2 ms^-1

• 2 ms^-1 in the opposite direction of the train

• zero

82.

A motorboat covers a given distance in 6 h moving downstream on a river. It covers the same distance in 10 h moving upstream. The time it takes to cover the same distance in still water is

• 9 h

• 7.5 h

• 6.5 h

• 8 h

The displacement-time graph of two moving particles make angles of 30° and 45° with the X-axis. The ratio of their velocities is

• $\sqrt{3} : 2$

• 1 : 1

• 1 : 2

• $1 : \sqrt{3}$

In a lift moving up with an acceleration of 5ms^-2 dropped from a height of 1.25 m. The time taken by the ball to reach the floor of the lift is (g = 10 ms^-2)

• 0.3 s

• 0.2 s

• 0.16 s

• 0.4 s

A car moves from A to B with a speed of 30 km/h and from B to A with a speed of 20 km/h. What is the average speed of the car ?

• 25 km/h

• 24 km/h

• 50 km/h

• 10 km/h

A body starts from rest and moves with constant acceleration for t sec. It travels a distance x₁ in first half of time and x₂ in next half of time, then

• x₂ = x₁

• x₂ = 2x₁

• x₂ = 3x₁

• x₂ = 4x₁

The velocity-time graph for two bodies A and B are shown in figure. Then, the acceleration of Aand B are in the ratio

• sin 25° to sin 50°

• tan 25° to tan 40°

• cos 25° to cos 50°

• tan 25° to tan 50°

A body falls freely for 10 s. Its average velocity during this journey is (Take, g = 10 ms^-2)

• 100 ms^-1

• 10 ms^-1

• 50 ms^-1

• 5 ms^-1

From the top of a tower a stone is thrown up which reaches the ground in a time t₁. A second stone thrown down with the same speed reaches the ground in a time t₂. A third stone released from rest from the same between reaches the ground in a time t₃. Then

• $\frac{1}{{\mathrm{t}}_3} = \frac{1}{{\mathrm{t}}_2} - \frac{1}{{\mathrm{t}}_1}$

• ${\mathrm{t}}_3^2 = {\mathrm{t}}_1^2 - {\mathrm{t}}_2^2$

• ${\mathrm{t}}_3 = \frac{{\mathrm{t}}_1 + {\mathrm{t}}_2}{2}$

• ${\mathrm{t}}_3 = \sqrt{{\mathrm{t}}_1 {\mathrm{t}}_2}$

If the magnitude of sum of two vectors is equal to the magnitude of difference of the two vectors, the angle between these vectors is,

• 90^o

• 45^o

• 180^o

• 0^o