Download Lab Mirterm Review PPT

Midterm Review
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• A car is travelling at 10 m/s when the driver steps
on the brake. The car begins decelerating at a
rate of 1 m/s/s.
a) How fast will the car travel in 3 seconds?
b) How far will the car travel in those 3 seconds?
• a) v  v0  at  10  1(3)  7 m / s
• b)
1 2
x  v0t  at  10(3)  0.5(1)(9)  30  4.5  25.5m
2
Object Thrown Up
• What is the instantaneous speed
at the highest point?
• 0
• What is the instantaneous speed
of the object at points of equal
elevation?
• The same.
• Is acceleration different when
the object moving upward or
downward?
• The same -9.8 m/s/s.
Independence of Horizontal and
Vertical Motion Demo
• Two balls released
simultaneously. One
ball dropped freely,
another projected
horizontally.
• Which ball will hit the
ground faster?
• Both balls fall the same
vertical distance in
equal times.
Projectile Launched at an Angle
• The horizontal motion of a projectile is independent of
its vertical motion.
• The horizontal velocity of a projectile is constant (a never
changing in value).
• The vertical velocity of a projectile changes by 9.8 m/s
each second.
Newton’s Laws of Motion
• 1. Every object continues in a state of rest, or of
uniform speed in a straight line, unless acted on
by a nonzero net force.
• 2. The acceleration produced by a net force on an
object is directly proportional to the magnitude
of the net force, and inversely proportional to the
mass of the object.
F
a
m
F  ma
• 3. Forces are always paired. The mutual forces of
action and reaction between two bodies are
equal in size and opposite in direction.
Study Guide
• 30.
F 200 N
2
a 
 20m / s
m
10
Friction
• Friction = µN=µmg
• µ-coefficient of friction
• N-normal force
• Frictional force always directed opposite to the motion.
• The magnitude of the frictional force depends on the
nature of the surfaces in contact.
• Frictional force is independent of
• the amount of surface in contact
• relative speed of the objects
Study Guide
• 38. Friction = µN=µmg =
= 0.3 x 1.5kgx10m/s/s/= 4.5N
• Describe velocity and acceleration of each
segment of the graph.
Accuracy and Precision.
• _________________describes how close a
measured value is to the true value.
• Accuracy
• _________________describes the degree of
exactness to which the measurement of a
quantity can be reproduced.
Motion Maps
• If the distance between dots increasing, the
object is speeding up or accelerating.
• If the distance between dots decreasing, the
object is slowing down or decelerating.