ESC 116F Chapter 3: Gravity and Motion
Select all that represent an object undergoing an acceleration.
- A ball falling off a table.(The falling ball is accelerated by gravity.) - A car braking to a stop.(Any change in velocity is an acceleration.) - A car turning a corner at 88 km/hr.(A change in direction is an acceleration.)
a rocket is in orbit around the earth. this means ____
- the force to hold the rocket in orbit is provided by gravity. - if the rocket fires its engine and changes its V, its orbit will change.(If V changes, Fcircular would no longer equal FG and the orbit would change.)
The force needed to keep an object moving in a circle (not necessarily an orbit) depends on
- the velocity of the object - the object's mass - the radius of the circle
Which of the following objects (essentially) maintain a constant velocity?
-A hockey puck sliding on the ice -An apple sitting on a table
In the absence of any forces, what keeps an object moving at constant speed?
Inertia
The tendency of a body at rest to remain at rest, or of a body moving in a straight line to remain moving in a straight line, is known as
Inertia
If two planets have the same mass, but one has four times the radius of the other, how will their escape velocities compare?
The large planet will have one-half the escape velocity of the small planet.
Observing the effect of gravity between a planet and its moon can allow us to determine the planet's
mass
If one planet is larger (in size) than another, its surface gravity ______.
might or might not be bigger
If two objects are accelerated to the same velocity, the more massive object requires ______ force.
more
The Moon orbits Earth, but a falling apple hits the ground. This is because
the Moon also has a "sideways" (compared to falling) velocity
newtons ______ law of motion is that two interacting bodies produce a pair of equal and opposite forces on each other
third
An orbit that is nine times farther from a black hole will have a circular velocity that is ______ than the closer orbit.
three times slower
Compared to the gravitational force between two bodies with masses of 100 kg and 200 kg, the gravitational force between two bodies the same distance apart with masses of 100 kg and 400 kg is Blank
twice as much
A dropped apple falls because of the force of gravity between it and Earth. The force on Earth is
upward and equal
Newton's law of inertia states that a moving body maintains a constant ______, moving in a _____line, unless a ______ acts on it.
velocity; straight; force
Compared to being on Earth, on Mars your
weight will be different and your mass the same
Which of the following cases correctly describe orbiting objects?
-When one object is very massive compared to the other object, the center of the balance point of the orbit can be inside the massive object. -As a result of Newton's second and third laws, the smaller body moves more. -Two equally massive bodies orbit each other equally.
The image demonstrates Figure 3.4
-how something can be forever "falling" but not hit Earth -"Newton's cannon," a thought experiment
The ball will move faster if the person ______.
-lets out some string and exerts the same force -exerts a stronger force on the string
Astronomers might use the modified version of Kepler's third law to determine
-the total mass of a binary star system -the mass of a nearby star with planets -the mass of a Kuiper belt dwarf planet and its moon
The same force is applied to all the objects. Arrange them according to how much acceleration they experience, from the most (top) to the least (bottom).
1. A Ping-Pong Ball. 2. A tennis ball. 3. A bowling ball. 4. A golf cart.
Match the terms and definitions. 1. Acceleration 2. Velocity 3. Mass 4. Force
1. A change in speed, direction, or both. 2. Velocity: The speed and direction of an object. 3. Mass: The amount of matter in an object. 4. Force: Something that causes a change in speed, direction,or both.
Rank the following objects by how much inertia they have, from least (top) to most (bottom). A leaf falling from a tree The Sun The Moon orbiting Earth A house A car Driving on the highway
1. A leaf falling from a tree 2. a car driving on a highway 3. a house 4. the moon orbiting the Earth 5. The sun
Match each example of motion with whether it is a speed or a velocity. 1. Speed 2. Velocity
1. Speed -88 mph -4 cm/yr 2. Velocity -1000 km/s north -11.4 km/s up
Match the correct missing words with each statement. 1. The same as 2. Larger than 3. Smaller than
1. The same as: 2. Larger than: 3. Smaller than:
If quantity A is directly proportional to quantity B, then if B increases 10 times, A must increase
10
Reducing the separation of two bodies to one-fourth its original value will cause the gravitational force between them to become ____ times ______.
16 ; stronger.
The gravitational force between two asteroids is 100 N. If the distance between them doubles, the gravitational force will be _____.
25n
An astronaut floating in space throws a wrench, exerting a 20 N force. The astronaut
An astronaut floating in space throws a wrench, exerting a 20 N force. The astronaut
Which fundamental force plays the most important role in shaping the structure of the Universe?
Gravity
An astronaut in space swings a ball on a string in a circle. If the string breaks, the ball will
Moving in a straight line
A coconut falling from a tree is an example of
Newton's second law of motion.(The force of gravity causes the apple to accelerate.)
Consider two skateboarders labeled X and Y. When X exerts a force on Y, Y exerts an equal force on X. This scenario serves as an example of
Newton's third law of motion
Which idea or equation best explains the different accelerations (arrows) shown in the picture? Figure 3.10
Newtons secons law
Select the planet that would have the same surface gravity as Earth.
One with nine times the mass and three times the radius.
If the period and separation of binary stars are known, then a modified version of Kepler's third law can be used to determine the system's
Total mass
If astronomers know the period and semimajor axis of the orbit of a planet circling a nearby star and have some independent way to determine the mass of the star, they have enough information to determine the mass of the planet.
True
If the same force acts on one cart with a mass of 5 kg and another with a mass of 10 kg, the 5 kg cart will be accelerated _______ as much as the 10 kg cart.
Twice
An object moving in uniform motion, if it changes its speed or direction such motion is defined as
acceleration
velocity is the speed an object must attain to overcome a planet's gravitational force and move into space.
escape
You apply a 12 N force to a 3 kg mass. The acceleration it produces is
four (a = F/m. a = 12/3. a = 4 m/s^2.)
Match the descriptions to either g or G.
g -stands for surface gravity on Earth. -is an acceleration. -can be used to compare weight on different planets. G -is used in Newton's law of gravity. -is the same everywhere in the universe.
The ______ force is the fundamental force that gives the Universe its structure.
gravitational
The idea that a force exists between two bodies that depends on the product of their masses and the square of the distance between them is known as the universal law of
gravity
For the same radius, the larger a planet's mass, the_____ the escape velocity
greater
A car turns a corner, and the Moon orbits Earth. There is more inertia overcome in changing the Moon's direction because
it is much more massive.
If a spacecraft launched from Earth doesn't have sufficient velocity,
it won't break free of Earth's gravity
The speed of an object is how fast it moves--how far it goes over a period of time. The velocity of an object is
its speed and the direction it travels
While driving at a high speed, you suddenly slam on the brakes. An unsecured bag on the seat will
slide forward due to its inertia
Based on the equation, we can conclude that moons that are farther out from a planet have M= dV^2/G
slower obrital speeds
______ is the term for the acceleration of gravity near a body's surface.
surface graivity
Astronauts sometimes train in water tanks because the buoyancy of water exerts a force that opposes the pull of Earth's gravity. In the tank, the _____, of the astronauts and their equipment decreases, but the _____, which affects how hard is is to move them, stays the same.
weight; inertia
