HARD
JEE Main/Advance
IMPORTANT
Earn 100

The velocity of a particle moving in the positive direction of the x-axis varies as v=αx where α is a positive constant. Assuming that at the moment t=0 the particle was located at the point x=0, find:

a The time dependence of the velocity and the acceleration of the particle.

b The mean velocity of the particle averaged over the time that the particle takes to cover the first s metres of the path.

Important Questions on Kinematics

HARD
JEE Main/Advance
IMPORTANT

When a model rocket is launched, the propellant burns for a few seconds, accelerating the rocket upward. After burnout, the rocket moves upward for a while and then begins to fall. A parachute opens shortly after the rocket starts down. The parachute slows the rocket to keep it from breaking when it lands. The figure here shows velocity data from the flight of the model rocket. Use the data to answer the following.

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a How fast was the rocket climbing when the engine stopped? 

b For how many seconds did the engine burn?

c When did the rocket reach its highest point? What was its velocity then?

d When did the parachute open up? How fast was the rocket falling then?

e How long did the rocket fall before the parachute opened?

f When was the rocket's acceleration greatest?

g When was the acceleration constant? What was its value then (to the nearest integer)?

HARD
JEE Main/Advance
IMPORTANT

A particle of mass 10-2 kg is moving along the x-axis under the influence of a force Fx=-K2x2, where K=10-2 N m2. At the time t=0 it is at x=1.0 m and its velocity is v=0. Find:

a Its velocity when it reaches x=0.50 m.

b The time at which it reaches x=0.25 m.

HARD
JEE Main/Advance
IMPORTANT
A parachutist jumps from height 100 m. He wants to reach the ground with zero velocity. For this purpose, he switches on a parachute propeller after falling freely for a certain height. Given that after the parachute propeller is switched on the total acceleration of the man varies with velocity as a=-2v, where v is the instantaneous velocity of the man. Find the time after falling freely, man should switch on parachute propeller for this purpose. (Use g=10 m s-2)
HARD
JEE Main/Advance
IMPORTANT
Position (in m) of a particle moving on a straight line varies with time (in s) as x=t33-3t2+8t+4 m. Consider the motion of the particle from t=0 to t=5 s. Here, s1 is the total distance travelled and s2 is the distance travelled during retardation. Find s1s2.
HARD
JEE Main/Advance
IMPORTANT
The maximum possible acceleration of a train starting from the rest and moving on a straight track is 10 m s-2 and maximum possible retardation is 5 m s-2. The maximum speed that a train can achieve is 70 m s-1. Minimum time in which the train can complete a journey of 1000 m ending at rest is 3472α sec. Where α is an integer. Find α.
HARD
JEE Main/Advance
IMPORTANT
A train stopping at two stations 2 km apart on a straight line takes 4 minutes for the journey. Assuming that its motion is first uniformly accelerated and then uniformly retarded. Prove that 1x+1y=4, where x and y are the magnitude of the acceleration and retardation, respectively, in km min-2
HARD
JEE Main/Advance
IMPORTANT

Two particles are thrown from the top of a tower with the same speed in upward and downward directions simultaneously. If the first particle hits the ground in time t and the second particle takes time t0 after the first one hitting the ground to hit the ground. Then find

a Maximum height attained by the second particle above the tower.

b Height of tower 

HARD
JEE Main/Advance
IMPORTANT

A particle moves along x-axis in a positive direction. Its acceleration a is given as a=cx+d, where x denotes the x-coordinate of particle, c and d are positive constants. For velocity-position graph of particle to be of type as shown in figure, find the value of speed (in m s-1) of particle at x=0. Take c=1 s-2 and d=3 m s-2

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