IDENTIFY: Apply x x0 = v0 xt + 1 axt 2 to the motion of each train. A collision means the front of the passenger
train is at the same location as the caboose of the freight train at some common time.
SET UP: Let P be the passenger train and F be th
Phyx 125-1, Quiz 6
1) Jupiter has four large moons called the Galilean satellites, because Galileo was the first person to see
them. The table below contains some basic data. You may assume the orbits around Jupiter are circular.
a) (5 points) From the da
Phyx 125-1, Quiz 5
1) A very light bar (zero mass) of length L is attached to a wall by a
frictionless pivot, and is held in place by a cable attached to its end, as
shown at right. There is a 10 kg mass attached to the center of the bar.
a) (4 points) Wh
Phyx 125-1, Quiz 4
1) A uniform disk with a mass of 8 kg is being acted
on by three forces as shown at right. The disk is fixed
to a frictionless axle at its center.
a) What is the angular acceleration of the disk?
b) If the disk is initially stati
Phyx 125-1, Quiz 3, Solutions
1) A puck of mass 5 kg is sliding on a frictionless surface
at 2 m/s. It strikes a second, identical puck which is
initially stationary. Afterwards, the first puck moves away
at 30 above the horizontal while the second puck m
Phyx 125-1, Quiz 2
1) Two masses are connected by a cord on a
massless, frictionless pulley as shown at right.
The 5.7 kg mass has a coefficient of static friction
of 0.70 and a coefficient of sliding (kinetic)
friction of 0.42 with the ramp. The masses a
Phyx 125-1, Quiz 1
1) In a circus stunt of lunatic daring, an
acrobat atop a 15 m platform is shot
from a cannon at v = 40 m/s and with an
angle of 55 relative to the horizontal.
At the same instant the cannon is fired,
a motorcyclist is roaring along the
IDENTIFY: Eqs. 8.24 and 8.25 apply, with object A being the neutron.
SET UP: Let +x be the direction of the initial momentum of the neutron. The mass of a neutron is mn = 1.0 u .
1.0 u 2.0 u
EXECUTE: (a) v A 2 x = A
v A1x = v A1x / 3.0 . The s
IDENTIFY: Apply Eq. 8.9 to relate the change in momentum of the momentum to the components of the average
force on it.
SET UP: Let +x be to the right and +y be upward.
EXECUTE: (a) J x = px = mv2 x mv1x = (0.145 kg)( [65.0 m/s]cos30 50.0 m/s) = 15.4
IDENTIFY: For the system of two blocks, only gravity does work. Apply Eq.(7.5).
SET UP: Call the blocks A and B, where A is the more massive one. v A1 = vB1 = 0 . Let y = 0 for each block to be
at the initial height of that block, so y A1 = yB1 = 0 .
IDENTIFY: All forces are constant and each block moves in a straight line. so W = Fs cos . The only direction the
system can move at constant speed is for the 12.0 N block to descend and the 20.0 N block to move to the right.
SET UP: Since the 12.0 N
F = ma to the point where the three wires join and also to one of the balls. By symmetry
the tension in each of the 35.0 cm wires is the same.
SET UP: The geometry of the situation is sketched in Figure 5.81a. The angle that each wir
IDENTIFY: If the box moves in the + x-direction it must have a y = 0, so
The smallest force the child can exert and still
produce such motion is a force that makes the
y-components of all three forces sum to zero,
but that doesnt have any x-
IDENTIFY: Apply Eq. (3.30).
SET UP: T = 24 h .
4 2 (6.38 106 m)
= 0.034 m/s 2 = 3.4 103 g .
EXECUTE: (a) arad =
(24 h)(3600 s/h) 2
4 2 (6.38 106 m)
= 5070 s =1.4 h.
9.80 m/s 2
EVALUATE: arad is proportional to 1/ T 2 , so to increase arad by a fact
IDENTIFY: The equipment moves in projectile motion. The distance D is the horizontal range of the equipment
plus the distance the ship moves while the equipment is in the air.
SET UP: For the motion of the equipment take + x to be to the right and +
Phyx 125-1, Quiz 7 Solutions
1) A pendulum is made of a long thin bar of length 0.8 m, attached to a
thin disk of radius 0.15 m. The center of the disk is 0.6 m from the upper
end of the bar. The disk and the bar have equal masses. What is the
period of t