Vocabulary
A place where the position has been given a value of zero.
Origin
Which has more mass, a kilogram of feathers or a kilogram of iron?
a. The feathers
b. The iron
c. Neither—they both have the same mass.
Does a person's mass change when they go to space?
No, their weight changes.
What is the proper unit of Mass?
kg
How much mass does a 50,000 N truck have?
w = mg
50,000 N = m (9.8 m/s^2)
5,102 kg
Describes how quickly an object moves, calculated by dividing the distance traveled by the time it takes
Speed
Compared to its weight on Earth, a 10-kg object on the moon will weigh
a. the same amount.
b. less.
c. more.
Can Acceleration have a negative value?
Yes, it has direction- Speed cannot be negative.
What is the proper unit of Velocity?
m/s
Calculate the weight of a 60kg person on Mars. (g = 3.7 N/kg on Mars).
W = mg
60kg * 3.7 N/kg
222 Newtons
The rate at which velocity changes
Acceleration
After a cannonball is fired into frictionless space, the amount of force needed to keep it going equals
a. zero, since no force is necessary to keep it
moving.
b. twice the force with which it was fired.
c. one half the force with which it was fired.
d. the same amount of force with which it was
fired.
e. one quarter the force with which it was fired.
What is the formula for acceleration?
a = Vfinal - Vinitial / time
What is the proper unit of Acceleration?
m/s^2
Two ropes are used to support a box weighing 1,700 Newtons. One rope has a F Tension of 650 Newtons. What is the F Tension exerted on the second rope?
F Tension = F Gravity
1,700 N - 650 N
= 1,050 N
A variable that gives direction information included in its value
Vector
According to Newton's third law, if you push gently on something, it will push
a. gently on something else.
b. on you only if you aren't moving.
c. gently on you.
d. on something only under the right conditions.
What is the relationship between net forces and balances forces?
Equilibrium! If net forces are zero, an object is in equilibrium. If not, there is a change in motion or direction or both.
What is the proper unit of Force?
Newtons
A car has a mass of 1,000 kg. If a net force of 2,000 N is exerted on the car, what is its acceleration?
F = ma
a = F/m
a = (2,000 N) / (1,000 kg) = 2 m/s^2
An object moving through space and affected only by gravity
Projectile
How does acceleration of an object change in relation to its mass? It is
a. directly proportional.
b. acceleration doesn't depend on mass at all.
c. inversely proportional.
Explain the Law of Conservation of Momentum.
As long as two interacting objects are not influenced by outside forces (like friction), the total amount of momentum is constant.
What are the proper units of Momentum?
kg-m/s
A park bench with a weight of 760 Newtons is placed in a park. A woman with a weight of 530 Newtons sits down on it for a rest. Draw a diagram explaining the action reaction forces with the above system and the ground.
The woman and the bench both push down on the ground with a total weight of 1,290 N. The ground pushes upwards on both of them with a Normal Force of 1,290 N.