A ball hangs from a string inside a train moving along a horizontal straight track. The string is observed to incline towards the rear of the train making a constant small angle with the vertical. It shows that the train is

• moving with a uniform acceleration

• moving with a uniform velocity

• moving with a uniform retardation

• moving with an acceleration which is increasing uniformly

A particle moves along Y-axis in such a way that its y-coordinate varies with time t according to the relation y = 3 + 5t² + 7t². The initial velocity and acceleration of the particle are respectively

• 14 ms^-1 , − 5 ms^-2

• 19 ms^-1 , − 9 ms^-2

• 5 ms^-1 , 14 ms^-2

• 3 ms^-1 , − 5 ms^-2

An object travels north with a velocity of 10 ms^-1 and then speeds up to a velocity of 25 ms^-1 in 5 s. The acceleration of the object in these 5 s is

• 3 ms^-1 in north direction

• 3 ms^-2 in north direction

• 15 ms^-2 in north direction

• 3 ms^-2 in south direction

An automobile in travelling at 50 km/h, can be stopped at a distance of 40 m by applying brakes. If the same automobile is travelling at 90 km/h, all other conditions remaining same and assuming no skidding, the minimum stopping distance in metres is

• 72

• 92.5

• 102.6

• 129.6

65.

A rifle shoots a bullet with a muzzle velocity of 500 ms^-1 at a small target 50 m away. To hit the target the rifle must be aimed (take g = 10 ms^-2)

• exactly at the target

• 10 cm below the target

• 5 cm above the target

• 5 cm below the target

While driving a car around a curve of 200 m radius, the driver notices that a simple pendulum hung to the roof of the car is making an angle of 15° to the horizontal. The speed of the car in km/h is

• 60.5 

• 72.5

• 82.5

• 92.5

A man weighs 80 kg on earth surface. The height above ground where he will weigh 40 kg, is : (radius of earth is 6400 km)

• 0.31 times r

• 0.41 times r

• 0.51 times r

• 0.61 times r

A train moves from one station to another in 2 hours time. Its speed-time graph during this motion is shown below. The maximum acceleration during the journey is

• 140 kmh^-2

• 160 kmh^-2

• 100 kmh^-2

• 120 kmh^-2

A body dropped from a height h with an initial speed zero reaches the ground with a velocity of 3 km/h. Another body of the same mass was dropped from the same height h with an initial speed 4 km/h will reach the ground with a velocity of

• 3 km/h

• 4 km/h

• 5 km/h

• 12 km/h

A boat man can row with a speed of 10 km/h in still water. If the river flows at 5 km/h, the direction in which the boat man should row to reach a point on the other bank directly opposite to the point from where he started is (width of the river is 2 km)

• in a direction inclined at 120° to the direction of river flow

• in a direction inclined at 90° to the direction of river flow

• 60° in the north-west direction

• should row directly along the river flow