A projectile can have the same range R for two angles of projection. If t₁ and t₂ be the times of flights in the two cases, then the product of the two time of flights is proportional to

• R²

• 1/R²

• 1/R

• 1/R

A particle is moving eastwards with a velocity of 5 m/s in 10 seconds the velocity changes to 5 m/s northwards. The average acceleration in this time is

• towards north-east
• towards north.

• zero

• zero

A particle located at x = 0 at time t = 0, starts moving along the positive x-direction with a velocity ‘v’ that varies as v= α√x . The displacement of the particle varies with time as

• t³

• t²

• t

• t

A car starting from rest accelerates at the rate f through a distance S, then continues at constant speed for time t and then decelerates at the rate f/2 to come to rest. If the total distance traversed is 15 S, then

• S=ft

• S= ft²/72

• S = 1/2 ft²

• S = 1/2 ft²

A parachutist after bailing outfalls 50 m without friction. When a parachute opens, it decelerates at 2 m/s². He reaches the ground with a speed of 3 m/s. At what height, did he bail out?

• 91 m

• 182 m

• 293 m

• 293 m