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A high school physics class performs a set of experi-
ments, in which they examine the properties of a collision.
The students place two different pucks, puck A with a mass
of 2 kg and puck B with a mass of 3 kg, each with negli-
gible diameter, on an air hockey table. When the air is
flowing, the hockey table serves as a frictionless surface.
Now, the 2 kg mass is traveling 45 degrees north of east, and the 3 kg mass is traveling 45 degrees north of west, both at the same speed. So, the 3 kg mass has more momentum. When they collide, what will be the net force vector from the 3kg mass to the 2 kg mass? The explanation says that the force will point directly to the left. However, I'm not so sure. The 3 kg mass would also push the 2 kg upwards a bit too, wouldn't it? why wouldnt there be any forces in the y direction?
Here is the explanation. Puck a is 2 kg and puck b is 3 kg.Look at the initial conditions of the pucks before they collide. Puck A and puck B are trav-
eling with the same velocity. They are traveling in the y-direction with the same speed. They also
have the same speed in the x-direction, but in opposite directions. So when they collide, there
wont be any forces in the y-direction, which eliminates answer choices B and D. Since puck B
is coming from the right, the force it exerts on puck A will be from right to left, in the negative
x-direction; since the net acceleration of puck A is proportional to the net force, the correct
answer is choice C. Answer A is the acceleration puck B experiences due to colliding with puck
A.
ments, in which they examine the properties of a collision.
The students place two different pucks, puck A with a mass
of 2 kg and puck B with a mass of 3 kg, each with negli-
gible diameter, on an air hockey table. When the air is
flowing, the hockey table serves as a frictionless surface.
Now, the 2 kg mass is traveling 45 degrees north of east, and the 3 kg mass is traveling 45 degrees north of west, both at the same speed. So, the 3 kg mass has more momentum. When they collide, what will be the net force vector from the 3kg mass to the 2 kg mass? The explanation says that the force will point directly to the left. However, I'm not so sure. The 3 kg mass would also push the 2 kg upwards a bit too, wouldn't it? why wouldnt there be any forces in the y direction?
Here is the explanation. Puck a is 2 kg and puck b is 3 kg.Look at the initial conditions of the pucks before they collide. Puck A and puck B are trav-
eling with the same velocity. They are traveling in the y-direction with the same speed. They also
have the same speed in the x-direction, but in opposite directions. So when they collide, there
wont be any forces in the y-direction, which eliminates answer choices B and D. Since puck B
is coming from the right, the force it exerts on puck A will be from right to left, in the negative
x-direction; since the net acceleration of puck A is proportional to the net force, the correct
answer is choice C. Answer A is the acceleration puck B experiences due to colliding with puck
A.
