Show:
Uniform Circular Motion
Rotational Inertia and Center of Mass
Gravitation
Planetary Motion
100
How does the tangential speed differ for a merry go round with one horse on the outside of the ride and one horse halfway between the outside and the axis of rotation?
The horse that is further away from the axis of rotation will have a faster tangential speed.
100
How does increasing your rotational inertia change your rotational speed?
Increasing your rotational inertia decreases your rotational speed.
100
Explain what happens to the gravitational force between two objects when they move closer together.
The gravitational force increases.
100
What did Kepler say about the orbit of planets around the sun?
Elliptical shape, not circular
200
What happens to the tangential speed experienced by a rotating object when the distance from the object to the axis of rotation decreases?
Tangential speed decreases
200
When you stand with your back flat against a wall (your toes too), why can't you bend over and touch your toes?
Your center of mass is pushed too far forward and you lose your balance.
200
Explain what happens to the gravitational force when the distance between two objects increases.
The gravitational force decreases.
200
How was Ptolemy's model of the solar system different from Copernicus' model of the solar system?
Ptolemy believed in a geocentric model of the universe with the Earth at the center. Copernicus believed that in a heliocentric model of the universe with the Sun at the center and the planets moving in perfect circles around it.
300
An object is rotated at 4 m/s at a distance of 3.0 m away from the center of the circular path. What is the centripetal acceleration felt by the object?
5.3 m/s2
300
When you feel like you are going to lose your balance, you typically hold your arms out to the side. Explain why (in terms of rotational inertia) you do this.
Holding out your arms increases your rotational inertia which makes you more resistant to changes in rotational motion.
300
True or false: When you get far away enough from the sun, there is no gravitational force acting on you. Explain your answer.
False- there is always a gravitational force acting on you but when you move far enough away, the amount of force may be negligible.
300
How does Kepler's first law of planetary motion differ from Copernicus' theory of planetary motion?
Copernicus believed that the planets orbited around the sun in perfect circles but Kepler's first law states that the planets move in elliptical orbits around the sun with the sun at one of the foci.
400
Why is the tangential acceleration for an object in uniform circular motion zero?
The tangential velocity for an object in uniform circular motion is constant.
400
Compare and contrast rotational inertia and linear inertia (the inertia we talked about in our first two units of physics).
Linear inertia is the resistance to changes in direction or motion or an object moving in a straight line. Rotational inertia is the resistance to changes in a rotational state of motion.
400
Calculate the gravitational force acting between 5 kg and 8 kg objects that are 2 m apart.
6.67 x 10^-10 Newtons
400
What happens to the period of motion for planets as they are located further away from the sun?
The further a planet is located from the sun, the longer it takes to rotate around it (longer orbital period).
500
What provides the centripetal force for the following situations: 1. The moon orbiting around the Earth 2. A ball being whirled on a string 3. A car driving rapidly in a circle in a cement parking lot.
1. Gravitational force 2. Tension 3. Friction
500
What are the names of Ms. Collins' cats? (This is not a real question- I just needed a filler)
Baxter and Riley
500
If the mass of the sun were to suddenly double without changing the distance to any other planets, what would happen to the gravitational force acting on the earth?
It would double.
500
What happens to the orbital speed of planets around the sun as they are located further away from the sun?
The further a planet is located from the sun, the slower its orbital speed.