Two identical ice pucks, A and B

PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

Two identical ice pucks, A and B, each of mass

m

, slide without friction along a straight track that has been defined as the

x

-axis. At one instant puck A moves at

+3\,\text{m/s}

while puck B moves at

-4\,\text{m/s}

. Which statement best describes the total

x

-component of momentum

p_{x,\text{tot}}

of the two-puck system at that instant? (a)

p_{x,\text{tot}}

is positive with magnitude

7m

(b)

p_{x,\text{tot}}

is negative with magnitude

m

(c)

p_{x,\text{tot}}

is zero (d) The sign of

p_{x,\text{tot}}

cannot be determined without a numerical value for

m