Question

A molecule in a gas container hits a horizontal wall with speed 200 m s⁻¹ and angle 30° with the normal and rebounds with the same speed. Is momentum conserved in the collision? Is the collision elastic or inelastic?

Answer 1

Hii mate,

◆ Answers-
a) Momentum conserved
b) Elastic collision

◆ Explainations-
a) Whether the collision is elastic or inelastic total linear momentum of the system always remains costant.

b) Here, speed of the particle after rebounding remains same as before. Thus K.E. is same.
We know that K.E. is conserved in elastic collision, thus this collision is elastic.

Hope that helps you...

Answer 2

Answer:

Volume of the tank, V = 30 m3

Time of operation, t = 15 min = 15 × 60 = 900 s

Height of the tank, h = 40 m

Efficiency of the pump, η = 30 %

Density of water, ρ = 103 kg/m3

Mass of water, m = ρV = 30 × 103 kg

Output power can be obtained as:

P0 = Work done / Time = mgh / t

= 30 × 103 × 9.8 × 40 / 900 = 13.067 × 103 W

For input power Pi,, efficiency η, is given by the relation:

η = P0 / Pi = 30%

Pi = 13.067 × 100 × 103 / 30

= 0.436 × 105 W = 43.6 kW