Question

8. A ball moving with a momentum of 5 kg ms–1 strikes against a wall at an angle of 45° and
reflected at the same angle. The magnitude of change in momentum is (in Ns) [ ]
a) 20 b) 40 c) 50 d) 70

Answer 1

Answer:

hey there !!

=) As ball is moving with momentum 5kgm/s makes an angle 45° with horizontal to wall.

=) We know momentum is a vector quantity so resolving into components.

●------------------>5cos45

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v

5sin45

◆ p1 = (5cos45)i - (5sin45)j

now F.B .D of ball after striking

5cos45 <------●

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v

5sin45

◆ p2 = (-5cos45)i -(5 sin45)j

=) so change in momentum =( p2 - p1)

= -2× (5cos45)i

=) magnitude = 10cos45

= 10× 1/√2 = 5√2 kgm/s

=7.07kgm/s

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hope it will help u ^_^