Two friends, Al and Jo, have a combined mass of 180 kg. At the ice skating rink, they stand close together on skates, at rest and facing each other. Using their arms, they push on each other for 1 second and move off in opposite directions. Al moves off with a speed of 9.1 m/sec in one direction and Jo moves off with a speed of 10.9 m/sec in the other. You can assume friction is negligible.
What is the mass of Al?
Thank you so much for your help.
2007-06-15 10:42:38 · 5 answers · asked by goboilers21 2 in Science & Mathematics ➔ Mathematics
Principle: momentum is conserved.
So if mass of Al =x
Mass of Jo=180-x
Then 10.9 x = 9.1 *(180-x)
NOTE: mv is vector
Solve (masses will be about 82 and 98 kg)
2007-06-15 10:56:36 · answer #1 · answered by cattbarf 7 · 1⤊ 0⤋
Okay, remember they are stationary at the start so inertia is zero, so it must be zero at the end:
M(al)V(al)+M(jo)V(jo)=0
and we know total mass:
M(al)+M(jo) = 180
M(jo) = 180-M(al)
Insert into equation to get
M(al)V(al) + (180-M(al))V(jo)) = 0
By putting in the known values and rearranging you get Al to have a mass of 98.1kg
Jo is therefore only 81.9kg
:)
2007-06-15 10:54:35 · answer #2 · answered by Anonymous · 1⤊ 0⤋
10.9 + 9.1 = 20
180 / 20 = 9
9 x 9.1 = 81.9
al's mass = 81.9kg
2007-06-15 10:48:40 · answer #3 · answered by ? 3 · 1⤊ 0⤋
Al = 98.1 kg
Jo= 81.9 kg
2007-06-15 10:52:35 · answer #4 · answered by Yellow Tail 3 · 0⤊ 1⤋
the mass of al is bigger than cape verde
2007-06-15 10:45:33 · answer #5 · answered by Anonymous · 0⤊ 2⤋