Question

33. Give reasons for the following:
a wall.
a
(a) No work is done if a man is pushing against
(b) Hammer drives a nail into the wood only
al
he
g.
when it is lifted up and then struck.
(c) A horse and a dog are running with the same
speed. Which one of them has more kinetic
energy than the other ?
(d) A teacher moving around in the class is doing
work but a child standing and reading a book
is not doing any work.
​

Answer 1

Explanation:

C} option

I hope it may help to you

Answer 2

Answer ➪

(a) A wall does not move when pushed, hence the object is not moving. No work is done.

(b) When a hammer is lifted, the potential energy stored in it is used in driving the nail into the wood.

(c) When a horse and a dog are running at the same speed. The animal having more mass will have more kinetic energy. A horse has more mass than a dog, hence the kinetic energy of a horse is more than the kinetic energy of a dog.

(d) A child reading a book while standing is not moving from its place i.e. displacement is zero. Hence, no work is done by the child.

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