Question

Questions 18-20: A 5.0 kg marble slides to the left with a velocity of magnitude 2 m/s on the frictionless, horizontal surface of an icy, New York sidewalk and has a head-on collision with a larger 10 kg marble sliding to the right with a velocity of magnitude 5.0 m/s. The final speed of the 10kg ball is found to be 2 m/s to the left (10 points) IMPORTANT: MOMENTUM IS A VECTOR QUANTITY-SHOW ALL YOUR STEPS 18) Find the magnitude of the final speed of the Skg marble the collision _(4 pts) 19) Calculate the impulse of the net force on the 10 kg marble _(4 pts) 20) This is an elastic collision: a) True b) False c) NOT ENOUGH INFORMATION (2 pts) (SHOW BY CALCULATION) 21) State the condition of equilibrium of a mechanical system (8 points)

Answer 1

Ans

18)

We use the conservation of momentum before and after collision

m 10010 – m5U5 = m 10010 + m5u's

合 105 -5*2=10*2+5* l-

=us = 4m/s

19)

Impulse = mass * change in velocity = 10*(5-2) = 30 kgm/s

20)

We know elastic collision

U's - V10 010 - 05

4 – 2 = 5 – (-2)

= = = 0.285

Ans is false. It is not elastic collision

21)

Condition for equilibrium in a mechanical system

a) Net Force in the whole system is zero i.e the bodies are not accelerating

b) Net torque in the whole system should also be zero i.e no angular acceleration occurs.

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