# PHYS16 - Lecture 20 ```PHYS16 – Lecture 20
Review: Ch. 1-7
October 25, 2010
• TA Help Sessions
– Su 8-9 pm, W 8-9 pm, Sa 3-5pm
– Merrill 116 (around the corner from my office)
• Online Homework 8 due Sunday, Oct. 31
• Formal Lab Report due Monday, Nov. 1
Review Ch. 5 Energy
Practice Question 1
• I throw ball #1 up with an initial speed of v0,
and I throw ball #2 of equal mass down with
an initial speed of v0. Just before the balls hit
the ground what is the relationship of their
kinetic energies?
A)
B)
C)
D)
K1&gt;K2
K1=K2
K1&lt;K2
There is not enough information
Practice Question 2
• F(x)=3x^2+4. What is the work done from x =
1 m to x=3 m?
A)
B)
C)
D)
34 J
31 J
33 J
18 J
Practice Question 3
• A 300 kg car slows from 60 km/s to 10 km/s.
What is the work done on the car?
A)
B)
C)
D)
5.25E11 J
-5.25E8 J
-5.25E5 J
-5.25E11 J
Practice Question 4
• Which object has more kinetic energy?
A)
B)
C)
D)
E)
1 kg, 5 m/s
2 kg, 4 m/s
3 kg, 3 m/s
4 kg, 2 m/s
5 kg, 1 m/s
Practice Question 5
• Which object has more momentum?
A)
B)
C)
D)
E)
1 kg, 5 m/s
2 kg, 4 m/s
3 kg, 3 m/s
4 kg, 2 m/s
5 kg, 1 m/s
Practice Question 6
• A horizontal force of 60 N slides a block up a
10 m incline of 30 degrees. Ignore friction.
What is the work done by the force to get the
block up the ramp?
A) 60*10*cos(30)
B) 60*10*sin(30)
C) 60*cos(30)
D) 60*sin(30)
Ch. 6 Energy Conservation
Practice Question 1
• A 50-kg kid is sliding down a ramp with a
height of 4 m and a horizontal distance of 3 m.
If the frictional force is a constant 60 N, what
is the velocity of the kid at the bottom of the
ramp?
Practice Question 2
• A mass is attached to a horizontal spring of
spring constant 4N/m. If a weight attached to
the mass pulls the mass a distance of 0.5 m
from equilibrium, how much work was done
by the weight on the mass?
Ch. 7 Momentum
Practice Question 1
• In a perfectly inelastic collision the following is
not true?
B) E is conserved
C) P is conserved
D)F=dp/dt
Practice Question 2
• True or false. In an inelastic collision the
kinetic energy after the collision can be
greater than the kinetic energy before the
collision.
A) True
B) False
Practice Question 3
• In a click-clack if all balls have equal mass and
I take one ball out and put it at height 4 m,
how high should the ball on the other side go?
A) 4 m
B) 2 m
C) 0 m
D)There is not enough information
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