A body is falling freely under gravity. The distances covered by the body in first, second and third minute of its motion are in the ratio

• 1 : 4 : 9

• 1 : 2 : 3

• 1 : 3 : 5

• 1 : 5 : 6

A bullet fired into a fixed wooden block loses half of its velocity after penetrating 40 cm. It comes to rest after penetrating a further distance of

• $\frac{22}{3} \mathrm{cm}$

• $\frac{40}{3} \mathrm{cm}$

• $\frac{20}{3} \mathrm{cm}$

• $\frac{22}{5} \mathrm{cm}$

A ball A is thrown up vertically with a speed u and at the same instant another ball B is released from a height h. At time t, the speed of A relative to B is 

• u

• 2u

• u − gt

• $\sqrt{\left({\mathrm{u}}^2 - \mathrm{gt}\right)}$

A bullet is to be fired with a speed of 2000 ms^-1 to hit a target 200 m away on a level ground. If g = 10 ms^-2, the gun should be aimed

• directly at the target

• 5 cm below the target

• 5 cm above the target

• 2 cm above the target

A particle starts from rest at t = 0 and moves in a straight line with an acceleration as shown in figure. The velocity of the particle at t = 3 s is

• 2 ms^-1

• 4 ms^-1

• 6 ms^-1

• 8 ms^-1

Two cars A and B are moving with same speed of 45 km/h along same direction. If a third car C coming from the opposite direction with a speed of 36 km/h meets two cars in an interval of 5 min, the distance of separation of two cars A and B should be (in km)

• 6.75

• 7.25

• 5.55

• 8.35

47.

Two trains are moving with equal speed in opposite directions along two parallel railway tracks. If the wind is blowing with speed u along the track so that the relative velocities of the trains with respect to the wind are in the ratio 1 : 2, then the speed of each train must be

• 3u

• 2u

• 5u

• 4u

Two balls are dropped to the ground from different heights. One ball is dropped 2 s after the other but they both strike the ground at the same time. If the first ball takes 5 s to reach the ground, then the difference in initial heights is (g = 10 ms^-2)

• 20 m

• 80 m

• 170 m

• 40 m

A ball is thrown vertically upwards with a velocity of 25 ms^-1 from the top of a tower of height 30 m. How long will it travel before it hits ground ?

• 6 s

• 5 s

• 4 s

• 12 s

To cover a population of 20 lakh, a transmission tower should have a height (Radius of earth = 6400 km, populatton per square km=1000)

• 25 m

• 50 m

• 75 m

• 100 m