Question

Give scientific reasons.
a. When an object falls freely to the
ground, its acceleration is uniform.
Even though the magnitudes of
action force and reaction force are
equal and their directions
opposite, their effects do not get
cancelled.
c. It is easier to stop a tennis ball as
compared to a cricket ball, when
both are travelling with the same
velocity
d. The velocity of an object at rest is
considered to be uniform.​

Answer 1

Answer:

a)As both objects are experiencing the gravitational force which accelerate both objects with ~9.83 m/s².Mass of the object doesn't matter. But there is another force acting on the i.e. Bouyant force,if the density of the objects is close to the density of air,it can't be equal to the density of air,the object resist for short period of time.then it falls down. In vacuum resistance of air is absent

b) Even though the magnitudes of

action force and reaction force are

equal and their directions are

opposite, their effects do not get

cancelled because the action and reaction forces acts on different objects.

c) Objects with same velocity don't have same kinetic energy and momentum, unless the mass is same .

\begin{gathered}p = mv \\\end{gathered}

p=mv

k.e = \frac{1}{2} m {v}^{2}k.e=

2

1

mv

2

The mass of cricket ball is > the mass of tennis ball. Therefore it is easier to stop tennis ball as

compared to a cricket ball, when

both are travelling with the same

velocity.

d) The velocity of object at rest is zero and it is constant until the object is set in motion

Answer 2

The gravitational force is given as,

F=G

(R+h)

2

m

1

m

2

From the above equation, it is clear that,

F∝

(R+h)

2

1

Since, R>>h

So, the height can be neglected.

Thus, the gravity acting on a freely falling object is constant and therefore, the acceleration due to gravity is also constant

Explanation:

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