BRIDGING PROBLEM One Collision After Another Sphere A of mass 0.600 kg is initia
ID: 1363047 • Letter: B
Question
BRIDGING PROBLEM One Collision After Another
Sphere A of mass 0.600 kg is initially moving to the right at
Sphere B, of mass 1.80 kg, is initially to the right of
sphere A and moving to the right at After the two
spheres collide, sphere B is moving at in the same direction
as before. (a) What is the velocity (magnitude and direction)
of sphere A after this collision? (b) Is this collision elastic or inelastic?
(c) Sphere B then has an off-center collision with sphere C,
which has mass 1.20 kg and is initially at rest. After this collision,
sphere B is moving at 19.0° to its initial direction at
What is the velocity (magnitude and direction) of sphere C after
this collision? (d) What is the impulse (magnitude and direction)
imparted to sphere B by sphere C when they collide? (e) Is this
second collision elastic or inelastic? (f) What is the velocity (magnitude
and direction) of the center of mass of the system of three
spheres (A, B, and C) after the second collision? No external forces
act on any of the spheres in this problem.
SOLUTION GUIDE
See MasteringPhysics® study area for a Video Tutor solution.
IDENTIFY AND SET UP
1. Momentum is conserved in these collisions. Can you explain
why?
2. Choose the x- and y-axes, and assign subscripts to values
before the first collision, after the first collision but before the
second collision, and after the second collision.
3. Make a list of the target variables, and choose the equations
that you’ll use to solve for these.
2.00 m>s.
3.00 m>s
2.00 m>s.
4.00 m>s.
EXECUTE
4. Solve for the velocity of sphere A after the first collision. Does
A slow down or speed up in the collision? Does this make
sense?
5. Now that you know the velocities of both A and B after the
first collision, decide whether or not this collision is elastic.
(How will you do this?)
6. The second collision is two-dimensional, so you’ll have to
demand that both components of momentum are conserved.
Use this to find the speed and direction of sphere C after the
second collision. (Hint: After the first collision, sphere B
maintains the same velocity until it hits sphere C.)
7. Use the definition of impulse to find the impulse imparted to
sphere B by sphere C. Remember that impulse is a vector.
8. Use the same technique that you employed in step 5 to decide
whether or not the second collision is elastic.
9. Find the velocity of the center of mass after the second
collision.
EVALUATE
10. Compare the directions of the vectors you found in steps 6 and
7. Is this a coincidence? Why or why not?
11. Find the velocity of the center of mass before and after the first
collision. Compare to your result
Explanation / Answer
1> in the absence of any external force, linear momentum of the system remains conserved.
2> initial momentum = final momentum
if both the spheres were having same velocity then -
0.600 v + 1.80 v = 1.80 v' + 0.600 v''
if v' and v is in the same direction theen sphere A has to slow down beacuse of principle of conservation of linear momentum.
c> this collision is elastic collision.because in elastic collision kinetic energy of the system remains conserved.
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