MEDIUM
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A stone starts falling freely under gravity. The time taken by the stone to fall through the initial height h is 4 s. The further time taken to fall through the next 2h height will be closest to

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Important Questions on Motion in a Straight Line

HARD
Two uniformly dense spherical balls of radius R and 2R are released simultaneously from identical heights. If both the balls hit the ground at the same time, then the ratio of densities of the balls, ρR:ρ2R is (here, ρRis the density of the ball with radius R and ρ2R is the density of the ball with radius 2R)
EASY
A box filled with water has a small hole on its side near the bottom. It is dropped from the top of a tower. As it falls, a camera attached on the side of the box records the shape of the water stream coming out of the hole. The resulting video will show
 
EASY
Water-drops are falling at regular intervals from a water tap situated at a height of 5 meters from the ground. Just at the moment, the first drop touches the ground, the third drop comes out. At that moment, the height of the second drop of water from the ground will be
EASY
Two balls are released from the same position at a height of 500 m above ground, one after the other, with an interval of 1s. What is the distance between the two balls when the first hits ground?
(Acceleration due to gravity g=10 m/s2)
MEDIUM
A tennis ball is released from a height h and after freely falling on a wooden floor it rebounds and reaches height h/2. The velocity versus height of the ball during its motion may be represented graphically by: (graphs are drawn schematically and on not to scale)
EASY
A ball is projected vertically up with speed V0 from a certain height H. When the ball reaches the ground the speed is 3V0. The time taken by the ball to reach the ground and height H respectively are.(g=the acceleration due to gravity)
EASY
A stone is dropped from the top of a building. When it crosses a point 5 m below the top, another stone starts to fall from a point 25 m below the top. Both stones reach the bottom of building simultaneously. The height of the building is :
MEDIUM
From the top of a tower, a ball is thrown vertically upward which reaches the ground in 6 s. A second ball thrown vertically downward from the same position with the same speed reaches the ground in 1.5 s. A third ball released, from the rest from the same location, will reach the ground in _____ s.
MEDIUM
A ball is thrown vertically downward with a velocity of 20 m s-1 from the top of a tower. It hits the ground after some time with a velocity of 80 m s-1. The height of the tower is: g=10 m s-2
EASY
A person sitting in the ground floor of a building notices through the window, of height 1.5 m, a ball dropped from the roof of the building crosses the window in 0.1 s. What is the velocity of the ball when it is at the topmost point of the window? g=10 m s-2
EASY
A stone falls freely under gravity. It covers distance, d1 and, d2 in the first 4 seconds, and the next, 8 seconds respectively. The ratio d2d1 is
EASY
A body is thrown vertically upwards. Which one of the following graphs correctly represents the velocityv vs time t?
MEDIUM
Two balls A and B are placed at the top of 180 m tall tower. Ball A is released from the top at t=0 s. Ball B is thrown vertically down with an initial velocity u at t=2 s. After a certain time, both balls meet 100 m above the ground. Find the value of u in m s-1. [use g=10 m s-2]
HARD
A balloon was moving upwards with a uniform velocity of 10 m s-1. An object of finite mass is dropped from the balloon when it was at a height of 75 m from the ground level. The height of the balloon from the ground when object strikes the ground was around: (takes the value of g as 10 m s-2)
MEDIUM
An object of mass 5 kg is thrown vertically upwards from the ground. The air resistance produces a constant retarding force of 10 N throughout the motion. The ratio of time of ascent to the time of descent will be equal to : [Use g=10 m s-2].
EASY
A NCC parade is going at a uniform speed of 9 km h-1 under a mango tree on which a monkey is sitting at a height of 19.6 m. At any particular instant, the monkey drops a mango. A cadet will receive the mango whose distance from the tree at time of drop is :
(Given g=9.8 m s-2)
EASY
A ball of mass 0.5 kg is dropped from the height of 10 m. The height, at which the magnitude of velocity becomes equal to the magnitude of acceleration due to gravity, is _____ m. [Use g=10 m s-2 ]
EASY
A body is projected vertically upwards with a velocity 'u' from the top of a tower. Time taken by it to reach the ground is 'n' times the time taken by it to reach the highest point in its path. Height of the tower is
MEDIUM
A ball is dropped from the top of a 100 m high tower on a planet. In the last 12s before hitting the ground, it covers a distance of 19 m. Acceleration due to gravity (in m s-2 ) near the surface on that planet is______
MEDIUM
A bullet loses 1nth of its velocity passing through one plank. Considering uniform retardation, the number of such planks that are required to stop the bullet can be: