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2.Object A has mass m and is traveling forward with speed v . Which set of chang

ID: 1615825 • Letter: 2

Question

2.Object A has mass m and is traveling forward with speed v. Which set of changes to object A will not affect its momentum?

A)mass increased to 2m, speed increased to 2v

B)mass reduced to 0.25m, speed increased to 1.25v

C)direction of velocity reversed, speed kept at v

D)mass reduced to 0.5m, speed increased to 2v

Three balls are moving along a straight line. The diagram shows the mass, velocity, and instantaneous position of each ball. With the addition of a fourth ball (not shown the net momentum of the system is 0. Which could be the mass, velocity, and instantaneous position of the fourth ball? 8.00 m/s 6.00 m/s 2.00 m/s 5.00 m 7,000 m 2.00 kg 3.00 ke 4.00 kg O 2.00 kg, 5.00 m/s to the left, 12.0 m to the left of the 2.00-kg ball O 10.0 kg, 0.500 m/s to the left, 8.0 m to the left of the 2.00-kg ball O 1.00 kg, 10.0 m/s to the right, 12.0 m to the right of the 4.00-kg ball O 3.00 kg, 3.00 m/s to the left, 19.0 m to the left of the 2.00-kg ball

Explanation / Answer

Momentum of system is zero.

Pnet = 0

m1v1 + m2v2 + m3v3 + m4v4 = 0

+ve in right and -ve in left

m4v4 = -(6*3 + 4*2 - 8*2)

m4*v4 = -10 kg-m/sec

-ve sign means velocity of the fourth mass will be towards the left

Possible correct option is A.

2.

Initial momentum = P = mass *velocity = m*v

Option A, P = 2m*2v = 4mv

Option B, P = 0.25*m*1.25*v = 5mv/16

Option C, P = m*(-v) = -mv

Option D, P = 0.5*m*2*v = m*v

Correct option is D.