Unit 1: Intro
What are the MKS units for:
distance:
mass:
time:
meters, kg, seconds
Scalar quanitities have magnitude only. Magnitude is expressed by a _____ and a _______.
number
unit
Acceleration due to gravity, represented by the letter ____ is about _____ m/s2 in most of the USA.
g, 9.8
Newton's First Law is called the Law of Inertia. The best measure of an object's inertia is its ______.
mass
In the constant velocity car lab, what would have happened to distance between the marks on the paper if a faster car had been used?
They would have been spaced further apart.
Three basic quantities used in mechanics (study of motion) are: __________, ___________, and __________
distance, mass, time
Vector quantities have ______ and _____.
direction
If an object has uniform velocity, its acceleration = ____
zero
Newton's 2nd Law is also known as the Law of Acceleration. The mathematical expression of this law is ________________.
F = ma
If a faster car had been used, what would the resulting distance vs. time graph have changed?
The slope of the line would have been steeper.
What is the difference between weight and mass?
Mass is constant everywhere. Weight (a special kind of force) changes with location (e.g. earth vs. moon)
An airplane flies southward with a velocity of 922 km/h. There is a brisk tailwind (meaning blowing on the tail of the plane) with a velocity of 25 km/h. What is the resultant velocity of the plane?
922 km/h + 25 km/h = 947 km/h south
A kangaroo jumps up with an initial vertical velocity of 4.5 m/s. What will his final velocity be just before he lands?
4.5 m/s
Weight is a type of (inertia, force). On the moon, an object's mass would be (greater than, less than, the same as) on earth.
force, the same as
In the lab "The Weight" we investigated the relationship between mass and weight. We used a spring scale to weigh known masses. Next, we made a plot of "weight versus mass". What were the units of the slope of the line, and what did the slope represent?
Units were N/kg or m/s2
The slope of the line represented acceleration due to gravity (g) and was approximately 10 m/s2
Round the following to 3 significant figures:
2.8975 x 10-3
2.90 x 10-3
A small plane is flying east with a velocity of 155 km/h. The wind is blowing toward the east at a velocity of 35 km/h. An observer on the ground would measure the velocity of the plane to be:
a. 155 km/h, east b. 155 km/h, west
c. 120 km/h, east d. 190 km/h, east
d. 190 km/h, east
A tennis ball is dropped 1.2 m above the ground. With what velocity does it hit the ground (before the ground stops it)?
vf2 = 2gd
vf = sqrt(2gd) = sqrt(s*9.8*1.2) = 4.8 m/s
The weight of a child is 210 N. What is the child's mass?
F = mg
m = F / g = 210 / 9.8 = 21 kg.
On the moon, each kilogram of mass is pulled down with 1.6 newtons of weight. If you added a line to your graph showing the results of this activity if it had been done on the moon, how would the slope of the moon line compare to the slope of the earth line? Is it steeper (more vertical) or shallower (more horizontal)?
shallower
When graphing data, the ______ variable is placed on the x-axis, and the ______ variable on the y-axis.
independent / manipulated
dependent / responding
Two component vectors have magnitudes of 5 units and 8 units. The resultant of these vectors may have a magnitude of:
a. zero b. less than 3 units
c. more than 13 units d. any value from 3-13 units
d. any value from 3-13 units
A car is traveling at 16 m/s when the brakes are applied. The brakes decelerate the car at the rate of 5.0 m/s2. How long will it take to stop the car?
vf = vi + at
t = (vf - vi) / a
t = (0 - 16)/( -5) = 3.2 s
A bucket of water weight 110 N is being lifted by a person pulling upward on a rope with a force of 130N. Draw a diagram to help you.
a. What is the net force on the bucket?
b. What is the mass of the bucket?
F = 130 - 110 = 20N up
F = mg = 110N = m(9.8)
m = 110N/9.8 = 11 kg
In the Projectile Motion lab we predicted the landing spot for a steel ball which was launched horizontally from the chair. Our predicted range was quite different than our actual range. Name two factors that could account for the difference (error) between these?
distance from launch point to floor
height of the ramp
distance measured in horizontal direction