Recent Virginia Election

Day 8, Physics 131

Yes, regularly scheduled physics tutoring for June 2015 is here!

• Physics Tutoring Sessions Term I (June)• Monday: 4:00-6:00 pm, RRO 119 (Dylan Cromer)

Tuesday: 3:00-4:30 pm, RRO 119 (Gaither Frye)Wednesday: 4:00-6:00 pm, RRO 119 (Dylan Cromer)Thursday: 3:00-4:30 pm, RRO 119 (Gaither Frye)

HW Problem 9-5

• A 0.150-kg baseball is dropped from rest. • The magnitude of the baseball’s momentum is

0.780 kg m/s just before it lands on the ground.

• ? From what height was it dropped. ?

HW Problem 9-16

• When striking a volleyball, a player changes the velocity of the ball from 4.2 m/s to -24 m/s along a certain direction.

• ? If the impulse delivered to the ball is -9.3 kg m/s, what is the mass of the volleyball?

HW Problem 9-24

• An object initially at rest breaks into two pieces as the result of an explosion. One piece has twice the kinetic energy of the other piece.

• ? What is the ratio of the masses of the two pieces ?

• ? Which piece has the larger mass ?

HW Problem 9-34

• A 0.430-kg block is attached to a horizontal spring that is at its equilibrium length.

• Force constant k of spring is 20.0 N/m.• Block rests on frictionless surface.• A 0.0500-kg wad of putty is thrown

horizontally at the block, hitting it with a speed of 2.30 m/s and sticking.

• ? How far does the putty-block system compress the spring ?

HW Problem 9-37

• A 732-kg car stopped at an intersection is rear-ended by a 1720-kg truck moving with a speed of 15.5 m/s.

• ? If the car was in neutral and its brakes were off, so that the collision is approximately elastic, find the final speed of both vehicles after the collision ?

HW Problem 9-45

• See figure for a stack of three bricks, each of mass m and length L.

• ? Find the x coordinate of the center of mass of the bricks. ?

HW Problem 9-51, Pizza!

• The location of the center of mass of the partially-eaten 12-inch-diameter pizza shown in the figure is Xcm = -1.4 in. and Ycm = -1.4 in.

• Assume that each quadrant of the pizza is the same.

• ? Find the center of mass of the uneaten pizza above the x-axis (that is, the portion of the pizza in the second quadrant) ?

HW Problem 9-60• A 57.8-kg person holding two 0.880-kg bricks

stands on a 2.10-kg skateboard. Initially, the skateboard and the person are at rest. The person now throws the two bricks at the same time so that their speed relative to the person is 17.0 m/s.

• ?What is the recoil speed of the person and the skateboard relative to the ground, assuming the skateboard moves without friction.?

HW Problem 9-71

• A 1.35-kg block of wood sits at the edge of a table, 0.728 m above the floor.

• A 0.0105-kg bullet moving horizontally with a speed of 715 m/s embeds itself within the block.

• ? What horizontal distance does the block cover before hitting the ground ?