Presentation Rec.notebook
November 09, 2012
A ball of mass 0.150 kg is dropped from rest from a height
of 1.25 m. It rebounds from the floor to reach a height of
0.960 m. What impulse was given to the ball by the floor?
The front 1.20 m of a 1400 kg car is designed as a "crumple
zone" that collapses to absorb the shock of a collision. If a
car traveling 25.0 m/s stops uniformly in 1.20 m, (a) how
long does the collision last, (b) what is the magnitude of the
average force on the car, and (c) what is the acceleration of
the car? Express the acceleration as a multiple of the
acceleration of gravity.
Presentation Rec.notebook
November 09, 2012
Presentation Rec.notebook
November 09, 2012
How does the FORCE
FORCE
compare
How does the TIME OF FORCE
TIME OF FORCE
compare
What can be concluded?
Car 1
Car 2
Car 1
Car 2
Presentation Rec.notebook
November 09, 2012
3 A boy standing at one end of a floaƟng raŌ that is staƟon
relaƟve to the shore walks to the opposite end of the raŌ
away from the shore. As a consequence, the raŌ
A remains staƟonar
B moves away from the shore
C moves toward the shore
A 45.0 kg girl is standing on a 150 kg plank. The plank
originally at rest, is free to slide on a frozen lake, which is a
flat, frictionless surface. The girl begins to walk along the
plank at a constant velocity of 1.50 m/s to the right relative to
the plank. (a) What is her velocity relative to the surface of
the ice? (b) What is the velocity of the plank relative to the
surface of the ice?
Presentation Rec.notebook
November 09, 2012
A cannon is mounted on a railroad flatcar, the muzzle elevated
to 30.0o and pointed in the direction of the track. The cannon
fires a 1000 kg projectile at 1.00 km/s. (a) If the flatcar and
cannon together have a mass of 36000 kg, what is the initial
recoil speed of the flatcar? (b) In this problem, it appears that
momentum in the y-direction is not conserved. Explain what
happens to it?
Presentation Rec.notebook
Inelastic
November 09, 2012
Perfectly Inelastic
Elastic
4 A car and a large truck traveling at the same speed collide
head-on and sƟck together. Which vehicle undergoes the
larger change in the magnitude of its momentum?
A the car
B the truck
C
the change in the magnitude of momentum is the same
for both
D impossible to determine without more informaƟo
Presentation Rec.notebook
November 09, 2012
Inelastic Collisions
i
f
Perfectly Inelastic Collisions
i
f
Presentation Rec.notebook
November 09, 2012
Elastic Collisions
pi=pf
KEi=KEf
5 A small china bowl having kineƟc energy "E" is sliding along a
fricƟonless countertop when a server, with perfect Ɵming
places a rice ball into the bowl as it passes him. If the bowl
and rice ball have the same mass, what is the kineƟc energy of
the system thereaŌer
A 2E
B E
C E/2
D E/4
E E/8
Presentation Rec.notebook
November 09, 2012
Glancing Collisions
A railroad car of mass M moving at a speed v1 collides and
couples with two coupled railroad cars, each of the same
mass M and moving in the same direction at a speed v2. (a)
What is the speed vf of the three coupled cars after the
collision in terms of v1 and v2? (b) How much kinetic energy is
lost in the collision? Answer in terms of M, v1, and v2.
Presentation Rec.notebook
November 09, 2012
Two shuffle board disks of equal mass, one orange and the
other yellow, are involved in a perfectly elastic glancing
collision. The yellow disk is initially at rest and is struck by
the orange disk moving initially to the right at 5.00 m/s. After
the collision, the orange disk moves in a direction that makes
an angle of 37.0o with its initial direction. Meanwhile, the
velocity vector of the yellow disk is perpendicular to the
postcollision velocity vector of the orange disk. Determine
the speed of each disk after the collision.
Presentation Rec.notebook
November 09, 2012