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Explain why (a) A horse cannot pull a ...

Explain why
(a) A horse cannot pull a cart and run in empty space.
(b) Passengers are thrown forward from their seats when a speeding bus stops suddenly.
(c ) A cricketer moves his hands backwards when holding a catch.

Text Solution

Verified by Experts

(a) The horse cart will not have any reaction (as in case of ground) on it in empty space.
(b) Because of inertia.
(c ) As `F=Delta P//Delta t`, so if the player moves his hands backward, `Delta t` will increases and hencd F will decrease.
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Explain why? (a) a horse cannot pull a cart and run in empty space. (b) passengers are thrown forward from their seats when a speeding bus tops suddenly (c) It is easier to pull a lawn mower than to push it. (d)a cricketer moves his hands backwards while holding a catch

Why does a passenger fall forward when he alights from the moving bus ?

Knowledge Check

  • When a speeding bus stop suddenly, passengers are thrown forward from their seats because

    A
    the back of seat suddenly puushes the passengers forward.
    B
    inertia of rest stops the bus and takes the body forward.
    C
    upper part of the body continues to be in the state of motion whereas the lower part of the body in contact with seat remains at crest.
    D
    upper part of the body come to resst whereas the lower part of the body in contact with seat begins to move.

  • An inquistive student, determined to test the law of gravity for himself, walks to the top of a building og 145 floors, with every floor of height 4 m, having a stopwatch in his hand (the first floor is at a height of 4 m from the ground level). From there he jumps off with negligible speed and hence starts rolling freely. A rocketeer arrives at the scene 5 s later and dives off from the top of the building to save the student. The rocketeer leaves the roof with an initial downward speed v_0 . In order to catch the student at a sufficiently great height above ground so that the rocketeer and the student slow down and arrive at the ground with zero velocity. The upward acceleration that accomplishes this is provided by rocketeer's jet pack, which he turns on just as he catches the student, before the rocketeer is in free fall. To prevent any discomfort to the student, the magnitude of the acceleration of the rocketeer and the student as they move downward together should not exceed 5 g. Just as the student starts his free fall, he presses the button of the stopwatch. When he reaches at the top of 100th floor, he has observed the reading of stopwatch as 00:00:06:00 (hh:mm:ss:100 th part of the second). Find the value of g. (correct upt ot two decimal places).

    A
    `10.00 ms^(-2)`
    B
    `9.25 ms^(-2)`
    C
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    D
    `9.50 ms^(-2)`

  • Five persons A, B, C,D and E are pulling a cart of mass 100 kg on a smooth surface and cart is moving with acceleration of 3 m//s^(2) in east direction. When person A stops pulling, it moves with acceleration 1 m//s^(2) in the west direction. When person B stops pulling, it move with acceleration 24 m//s^(2) in the north direction. The magnitude of acceleration of the cart, when only A and B pull the cart keeping their direction same as the old directions, is :

    A
    `26 m//s^(2)`
    B
    `3 sqrt71 m//s^(2)`
    C
    `30 m//s^(2)`
    D
    `25 m//s`

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