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Question
Answer
The diagrams below show the velocity of an object before and after a force is applied. The magnitude of the velocity did not change.
Which of the following arrows represents the direction of the change in velocity?
B
iia) An aluminium sphere collides head-on with a stationary steel sphere. The two spheres move off separately after the collision.
State the principle of conservation of momentum.
The total momentum before = the total momentum after.
Provided no external force acts on the system.
iib) The aluminium sphere has an initial velocity of 10 m/s. Immediately after the collision the velocity of the steel sphere is 5 m/s.
Calculate the velocity v of the aluminium sphere immediately after the collision.
Mass of aluminium sphere = 2.7 kg
Mass of steel sphere = 7.9 kg
P = mv
2.7 x 10 = (2.7 x v) + (7.9 x 5)
V = (27 - 39.5) / 2.7 = -4.63 m/s
V = -4.6 m/s
Quantities in physics are classified as either vectors or scalars.
Which of the following units could only be used for a scalar quantity?
A - ms^-1
B - ms^-2
C - kg ms^-2
D - kg m^-3
D
Question
Answer
ia) P and Q are identical spheres. Sphere P moves along a smooth horizontal surface and collides with sphere Q, which is initially stationary. After the collision:
-sphere P moves off with a momentum of 0.096 kg m/s in a direction of 15 degrees to its initial direction.
-sphere Q moves off with a momentum of 0.14 kg m/s in a direction of 10 degrees.
Use a scaled vector diagram to show that the magnitude of the total momentum of spheres P and Q after the collision is about 0.2 kg m/s.
-construction of correct vector diagram, parallelogram or triangle, with all 3 directions and 0.096 kg m/s and 0.14 kg m/s labelled
-momenta correctly scaled (ratio lengths 0.14 to 0.096 rounds to between 1.40 and 1.50)
-horizontal resultant (to within a slope of 1 small square)
-total momentum = 0.22 to 0.24 kg m/s
ib) State the principle of conservation of linear momentum
The total momentum before collision = the total momentum after collision. Provided no external forces act on the system.