Astronomy 1400 Review for Test 2
•
study the “
summary of key concepts
” at the end of each chapter.
Chapter 4
1.
What is the difference between speed, velocity, and acceleration?
What are their units?
a.
Speed How fast and object is moving (distance/time)
b.
Velocity Speed and direction
c.
Acceleration Change in objects velocity
2.
Know the accomplishments of Sir Isaac Newton that we discussed in class.
a.
Explained all mechanics both celestial and earthly (Laws of motion and Force of Gravity)
b.
Invented Calculus
c.
Derives, corrects, expands Kepler’s Laws
d.
Wrote Philosophiae Naturalis Principia Mathematica
3.
What are Newton’s Three Laws of Motion?
Give some examples of Newton’s laws at work.
a.
1) A body at rest or in motion at a constant speed along a straight line remains in that state
unless acted upon by an outside force.
b.
2) A net force changes an objects momentum, accelerating it in the direction of the force.
Force= rate of change in momentum (momentum= mass x velocity)
For constant mass:
force=mass x acceleration so F=ma
c.
3) Whenever one body exerts a force on a second body, the second body exerts an equal
and opposite force on 1
st
body
4.
What is the mathematical definition of momentum and angular momentum?
a.
momentum= mass x velocity
b.
Angular momentum momentum in spinning =
mass x velocity x radius
5.
Explain briefly as we did in class how Newton’s Laws lead to the law of conservation on
momentum.
a.
An objects momentum
won’t change if object is left along
b.
But a force can change an object’s momentum
c.
However, an = and opposite force changes some other objects momentum by an = and
opposite amount
6.
What is angular momentum and torque?
What is the law of conservation of angular momentum?
a.
Torque anything that causes change in angular momentum
b.
Conservation of angular momentum:
As long as there is no external torque, the total angular momentum of a set interacting
objects cannot change.
7.
Do we need to constantly fuel planets to spin and revolve? Do spacecraft constantly need fuel for
propulsion through space? Why or why not?
a.
No since there is no drag in space the objects just keep moving in the way that they were
initially pushed
8.
What is the law of conservation of energy?
a.
Energy can not be created nor destroyed
9.
What are the three basic categories of energy?
a.
Kinetic
b.
Potential
c.
Radiative
10.
What is temperature on a microscopic level? How is temperature different from heat?
a.
Average kinetic energy of the particles (how fast they are moving)
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b.
Temperature is both a measure of heat and the density so even if something is hotter than
something else if the density is lower then it will still feel cooler.
11.
What does an objects gravitational potential energy depend upon?
a.
Mass
b.
Strength of gravity
c.
And distance which it falls
12.
Is energy stored in matter itself? What is the meaning of E=mc
2
?
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 Spring '07
 Holtz
 Astronomy, Solar System, Energy, Mass, Photon

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