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Bob Jones Science 9 Chapter 13 Mechanics


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The modern study of motion...
mechanics 13A
What is the proper way to begin the study of motion?
by describing motion 13A
The two parts of motion...
kinematics (the description of how things move) dynamics (why things move) 13A
A group of landmarks used to study motion.
frame of reference
Change in position of an object...
displacement 13A
Displacement over time...
speed 13A
Formula for velocity (or speed in a certain direction)
v=d/t 13A
units will be in m/s or km/hr
Formula for acceleration...
vf=final velocity 13A
vi=initial velocity
Newton's first law of motion...
an object in motion will stay in motion and an object at rest will stay at rest unless it is acted on by a force 13B
The resistance to change in motion...
inertia 13B
Newton's second law of motion...
The value of an unbalanced force is equal to its mass times its acceleration
F=ma 13B
Unit of force...
newton (N)
which are kg m/s2 13B
Newton's third law of motion...
For every action, there is an opposite and equal reaction 13B
Rockets take off by...
action-reaction forces
(third law)
What motion law are these:
When you car stops, you are thrown forward and a rocket in space doesn't have to burn feul to keep going straight?
First law
What motion law are these: when air resistance balances gravity, raindrops stop accelerating and a light bike can accelerate faster?
Second law
What law are these: When you lean against a wall, it supports you and when you dive from a boat, it moves backward.
third law
Quantities that give only magnitude such as speed, distance, or force are...
scalar 13A
Quantities that give magnitude and direction such as velocity are...
vectors 13A
A triangle symbol means...
change in 13A
Forces (such as gravity) that act on objects without touching them...
action-at-a-distance forces 13C
Who was the scientist that first experimented with gravitational attraction...
Galileo 13C
If a book and a bowling ball are dropped out of a plane which would hit first?
Both would hit at same time. 13C
If you drop a book and a feather on Earth and on the Moon, what would be different?
The book would hit first on Earth because the feather would have air resistance, but on the moon, they would hit together. 13C
On Earth, the acceleration due to gravity is..
9.8 m/s2
The distance that an accelerating object travels...
d=1/2 a t2
The highest velocity at which an object can fall...
its terminal velocity (when gravity is exactly balanced by resistance of the fluid its falling in)
Universal law of gravitation...
m1 time m2
F=G x __________
d squared
G in the universal gravitation formula is a fundamental...
physical constant
Satellites are...
celestial bodies in orbit around another celestial body

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