Measuring Motion
The description of an object changing position with respect to a frame of reference
What is motion?
The measurement of a change in velocity
What is acceleration?
The term in science for any action that can change the state of motion of an object
What is Force?
Find the velocity in meters per second of a baseball thrown 38 m from third base to first base in 1.7 s.
v = d/t = 38 m/1.7 s = 22 m/s toward first base
The force that resists the initiation of sliding motion between two surfaces that are in contact and at rest
What is static friction?
The scientific term used to describe the motion of an object relative to these reference points
What is frame of reference?
It is negative
Objects move in the direction of this force
What is the stronger/unbalanced force?
Find the average acceleration of a northbound subway train that slows down from 12 m/s to 9.6 m/s in 0.8 s.
a = (vf-vi)/t = (9.6 m/s - 12 m/s)/0.8s = -3 m/s2 north
The force that opposes the movement of two surfaces that are in contact and are moving over each other
The term which describes how far it is between the starting and ending points
What is displacement?
Acceleration can be altered in these three ways
What is speed up, slow down, or change in direction?
The unbalanced force that acts against the motion between two surfaces in contact and always opposes motion
What is friction?
Calculate the displacement in meters that a cyclist would travel in 5.00 h at an average velocity of 12.0 km/h to the southwest.
d = vt = 12.0 km/h * 5 h = 60.0 km
The kind of kinetic friction experienced if a rounded object rolls over a flat surface
What is rolling friction?
The formula for velocity
v = d/t
velocity = displacement/timeThe formula for acceleration
a = (vf-vi)/time
acceleration = (final velocity - initial velocity)/time
What are the force of gravity, the electromagnetic force, the strong nuclear force, and the weak nuclear force?
Mai's car accelerates at an average rate of 2.6 m/s2. How long will it take her car to speed up from 24.6 m/s to 26.8 m/s?
t = (vf-vi)/a = (26.8 m/s - 24.6 m/s)/2.6 m/s2 = 0.85 s
Name a way to lower unwanted friction
Use low-friction materials or use lubricants
The two quantities that must be measured in order to calculate speed
What is distance traveled and the time it took to travel that distance?
The type of acceleration which occurs with uniform circular motion
What is centripetal acceleration?
The greater type of friction
What is static friction?
A cyclist travels at a constant velocity of 4.5 m/s westward and then speeds up with a steady acceleration of 2.3 m/s2. Calculate the cyclist's speed after accelerating for 5.0 s.
vf = vi + at = 4.5 m/s + (2.3 m/s2 * 5.0 s) = 16 m/s
The strongest of the four fundamental forces
What is strong nuclear force?