# Physics - Momentum Question.

Q. A snooker ball of mass 0.350kg hits the side of a snooker table at right angles, and bounces off also at right angles. If its speed before collision is 2.8ms^-1 and its speed after is 2.5ms^-1, calculate the change in momentum.

BTW, it states the answer is NOT 0.105kgms^-1
nofronting
Q. A snooker ball of mass 0.350kg hits the side of a snooker table at right angles, and bounces off also at right angles. If its speed before collision is 2.8ms^-1 and its speed after is 2.5ms^-1, calculate the change in momentum.

BTW, it states the answer is NOT 0.105kgms^-1

Momentum is a vector quantity so you need to use velocity not speed. If you take the initial direction as positive, initial velocity u = 2.8m/s, final veloctiy v = -2.5m/s, change in momentum = 0.350(2.8 - (-2.5)) = 0.350*5.3 = 1.855 kgm/s
Bezza
Momentum is a vector quantity so you need to use velocity not speed. If you take the initial direction as positive, initial velocity u = 2.8m/s, final veloctiy v = -2.5m/s, change in momentum = 0.350(2.8 - (-2.5)) = 0.350*5.3 = 1.855 kgm/s

yeh, thats right.

Velocity has direction. if you say it is going towards the table edge with +ve velocity it must leave it with negative ( as its in the opposite direction)
Bezza
Momentum is a vector quantity so you need to use velocity not speed. If you take the initial direction as positive, initial velocity u = 2.8m/s, final veloctiy v = -2.5m/s, change in momentum = 0.350(2.8 - (-2.5)) = 0.350*5.3 = 1.855 kgm/s

Thanks, i did take it as a vector but, still got the wrong answer!