MEDIUM
JEE Main
IMPORTANT
Earn 100

A car moving at a constant velocity of 46 m s-1 passes a traffic cop who is readily sitting on his motorcycle. After a reaction time of 1.0 s, the cop begins to chase the speeding car with a constant acceleration of 4.0 m s-2 . How much time does the cop need to overtake the speeding car?

Important Questions on Motion Along a Straight Line

MEDIUM
JEE Main
IMPORTANT

You are driving towards a traffic signal when it turns yellow. Your speed is the legal speed limit of v0=55 km h-1. Your best deceleration rate has the magnitude, a=5.18 m s-2. Your best reaction time to begin braking is T=0.75 s. To avoid having the front of your car enter the intersection after the light turns red, should you brake to stop or continue to move at 55 km h-1 if the distance to the intersection and the duration of the yellow light are:
(a) 40 m and 2.8 s and
(b) 32 m and 1.8 s?
Give an answer of the brake, continue, either (if either strategy works), or neither (if neither strategy works and the yellow duration is inappropriate).

EASY
JEE Main
IMPORTANT
On a defence aircraft carrier, a military jet lands at a speed of 64 m s-1.
(a) Assuming the acceleration to be constant, what is the acceleration of the jet if it stops in 3.0 s due to the arresting cable that snags it?
(b) If the jet first touches at position xi=0, what is its final position along an x-axis lying under its landing path?
MEDIUM
JEE Main
IMPORTANT

You are arguing over a cell phone while trailing an unmarked police car by 25 m. Both your car and the police car are travelling at 120 km h-1. Your argument diverts your attention from the police car for 2.0 s (long enough for you to look at the phone and yell, "I won't do that!"). At the beginning of that 2.0 s, the police officer begins braking suddenly at 5.0 m s-2.
(a) What is the separation between the two cars when your attention finally returns? Suppose that you take another 0.40 s to realise your danger and begin braking.
(b) If you also brake at 5.0 m s-2, what is your speed when you hit the police car?

HARD
JEE Main
IMPORTANT

When a high-speed passenger train travelling at 161 km h-1 rounds a bend, the engineer is shocked to see that a locomotive has improperly entered onto the track from a siding and is a distance D=676 m ahead. When the locomotive is moving at 29.0 km h-1, the engineer of the high-speed train immediately applies the brakes. (a) What must be the magnitude of the resulting constant deceleration if a collision is to be just avoided? (b) Assume that the engineer is at x=0 when at t=0, he first spots the locomotive. Sketch x(t) curve for the locomotive and high-speed train for the cases in which a collision is just avoided and is not quite avoided.

Question Image

EASY
JEE Main
IMPORTANT
When startled, an armadillo will leap upward. Suppose it rises 0.558 m in the first 0.200 s.
(a) What is its initial speed as it leaves the ground?
(b) What is its speed at the height 0.544 m?
(c) How much higher does it go?
HARD
JEE Main
IMPORTANT

A man releases a stone at the top edge of a tower. During the last second of its travel, the stone falls through a distance of 925 h, where h is the tower's height. Find h.

MEDIUM
JEE Main
IMPORTANT
Raindrops fall 1800 m from a cloud to the ground. (a) If they were not slowed by air resistance, how fast would the drops be moving when they struck the ground?
(b) Would it be safe to walk outside during a rainstorm?
MEDIUM
JEE Main
IMPORTANT
A hot-air balloon is ascending at a rate of 14 m s-1 at a height of 98 m above the ground when a packet is dropped from it. (a) With what speed does the packet reach the ground and (b) how much time does the fall take?