Physics 113 –Morning Session, Summer 2006
To
be stapled on top of Participation Points #1, 2, 3
Student’s name _____________________ Total previous points
accumulated:
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10.1
Momentum
of the center of mass. A
1000 kg car at velocity v1=2.5 i
+ 10 j m/s skids on a frictionless icy road, it hits a 500 kg wagon
moving at v2= 4 i
+ j m/s. If they stay together, what is their velocity?
11.1
Inelastic
collision. A
1000 kg car moving at 10 km/h collides with a 1500 kg car moving in the same
direction at 5 km/h. The slower car is equipped with spring bumpers with spring
constant 20kN/m. Find the maximum compression of the spring.
11.2
Elastic
collision. While
playing a ball in the street, a child accidentally tosses a ball at 20m/s
toward the front of a car moving toward him at 15 m/s. What is the speed of the
ball after it rebounds elastically from the car?
12.1
Torque. A torque of 100Nm is required to start a
revolving door. If a child can push 50N North while
the door is aligned in the SW direction, how far from the axis of rotation must
he apply this force?
12.2
Analog
of
12.3 Rolling motion. A
round object like a sphere or wheel may be characterized by a rotational
inertia of the form I=αMR2, with α a constant. Derive an
expression for the final speed of such an object if it starts from rest and rolls
without slipping down an incline of vertical height h.
13.1 Vector cross product. Find a force vector that when applied at the point x=2m, y=1m, will produce a torque τ=5 k Nm about the origin.
13.2
Angular momentum. A 5cm diameter baseball has a mass of 100g
and is spinning at 200 rad/s. What is the magnitude
of its angular momentum?
13.3 Conservation of angular momentum. A turntable of radius 20cm and rotational
inertia 0.01kg.m2 is spinning freely at 20rpm about its central
axis, with a 20g mouse on its outer edge. The mouse walks from the edge to the
center, find the new rotation speed.