Question

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10. The friction of the air causes a vertical
retardation equal to 10% of the acceleration
due to gravity. Take g=10m/s. The
maximum height and time to reach the
maximum height will be decreased by
1) 9%, 9%
2) 11%, 11%
359%, 10%
4) 11%,9%​

Answer 1

Answer:

correct option is B.

Given,

Retardation =10%

If there is no friction then,

By the equation of the motion,

v2=u2+2gh

v=0

h=2gu2

Now,

When there is air resistance 10% of the gravity.

geff=g+0.1g=1.1g

The maximum height will be,

h1=2gefu2

Therefore, the difference is h1−h

u22gef−2gu2

So,

Change in height is:

2gu2−2gefu2

=2gu2−2gu2(1−1011)

Thus the percentage change in height is:

=2gu2