Newton's First Law of Motion - Inertia
On the surface of Jupiter, the acceleration due to gravity is about 3 times that of Earth. What would be the mass of a 170-kg rock on Jupiter?
170 kg
How much does a 3.0-kg bag of bolts weigh?
24.9
How much (in newtons) does 0.60 kg of salami weigh?
6 N
A person weighs 650 N. What is the mass of the person?
65 kg
T/F? An astronaut weighs the same on Earth as in space.
False
Suppose you are on an airplane moving at high speed. If you flip a coin straight up it will land in your lap rather than a great distance behind you. Explain.
Inertia keeps the coin with you because the air inside the airplane, yourself, and the penny are all moving at the same horizontal velocity.
Mass
The amount of matter in an object
Weight
The force due to gravity acting on an object
State the law of inertia in its full form and give examples of how it works.
The law of inertia states that an object at rest will stay at rest and an object in motion will stay in motion unless acted upon by an unbalanced force. For example, when a car takes a sharp turn, people's bodies will move to the side. Also, a ball will continue to roll down a hill until unless friction of another force stops it.
T/F? An astronaut has the same mass on Earth as in space.
True
The law of inertia applies to
both moving and nonmoving objects.
SI Unit of Mass
kg
Compared to its weight on Earth, a 10-kg object on the moon will weigh
less
If the force of gravity suddenly stopped acting on the planets, they would
move in straight lines tangent to their orbits.
The astronomer Copernicus publicly stated in the 1500s that Earth
revolves around the sun.
A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. The reason this can be done is that
the milk carton has inertia.
Compared to its mass on Earth, the mass of a 10-kg object on the moon is
the same.
After a cannonball is fired into frictionless space, the amount of force needed to keep it going equals
zero, since no force is necessary to keep it moving.
The force required to maintain an object at a constant speed in free space is equal to
0
On the moon, the acceleration due to gravity is 1/6 that on Earth. What would be the weight of 0.9 kg of bologna on the moon?
1.5 N
How much (in newtons) does a 10.0-kg bag of grass seed weigh?
100 N
The mass of a lamb that weighs 110 N is about
11 kg
On the surface of Jupiter, the acceleration due to gravity is about 3 times that on Earth. How much would a 0.40-kg rock weigh on Jupiter?
12 N
A bag of sports equipment has a mass of 10.0 kilograms and a weight of
98 N
Force
A push or a pull
T/F? If a hockey puck were to slide on a perfectly frictionless surface, it will eventually slow down because of its inertia.
False
T/F? If you were to slide a hockey puck across a frictionless ice rink, there must be a horizontal force on it to keep it in motion.
False
T/F? The name of the astronomer who first publicly stated that Earth revolves around the sun is Galileo.
False
Friction
Force between two surfaces that are sliding past each other.
Write a short paragraph on the difference between mass and weight. Give examples.
Mass is the amount of matter in an object. Weight is the force of gravity on an object. Mass would not change from planet to planet because the amount of matter stays the same, but weight would because the gravitational pull varies. The two are proportional; twice the mass would mean twice the weight. But this doesn't make them equal.
Which has more mass, a kilogram of feathers or a kilogram of iron?
Neither—they both have the same mass.
SI Unit of Force
Newton
You and a friend are jumping on a trampoline. Why does Earth, which is rapidly orbiting around the sun, not move under your feet when you jump?
Newton's first law holds that your body moves along with Earth because it is not compelled to change its motion by an unbalanced force.
Inertia
Property that every material object has; Resists changes in an object's state of motion
An object weighs 30 N on Earth. A second object weighs 30 N on the moon. Which has the greater mass?
The one on the moon
Galileo found that a ball rolling down one inclined plane would roll how far up another inclined plane?
To nearly its original height
T/F? The reason a penny thrown straight up inside an airplane will come back to your hand is that you, the air inside the plane, and the penny are all moving at the same horizontal velocity.
True
Friction
comes from microscopic bumps that act as obstructions to the object's motion, is the name given to the force acting between surfaces sliding past one another, acts in a direction that opposes the motion of an object.
An object following a straight-line path at constant speed
has zero acceleration.
One object has twice as much mass as another object. The first object also has twice as much
inertia.
Friction is a force that always acts
opposite to an object's motion.
You would have the largest mass of gold if your chunk of gold weighed 1 N on
the moon
The law of inertia states that an object
will continue moving at the same velocity unless an outside force acts on it, will continue moving in a straight line unless an outside force acts on it, that is not moving will never move unless a force acts on it, at rest will remain at rest unless acted on by an outside force.