4. Circular motion and gravity Flashcards
What happens when an object moves in a circular pattern at a constant velocity?
It experiences centripetal acceleration.
Why does an object moving in a circular pattern at constant velocity experience centripetal acceleration?
It is a vector, and a change in either speed or direction causes acceleration.
Centripetal acceleration is dependent on tangential velocity, Vt, and what?
The radius of the circle.
Centripetal acceleration always points towards where>
The centre of the circle.
What is centripetal force?
The net force that’s the sum of all the forces that move an object along a circular path.
The centripetal force is directly proportional to what?
The object’s mass.
What is gravity?
An attractive force between two objects with mass.
The force of gravity is directly proportional to what?
Both objects’ masses.
What do Kepler’s laws explain?
How the planets move and how the speed of the planet’s orbit changes along its orbit around the sun.
What is tangential velocity?
The motion of an object around a circle, where the direction of the velocity is always tangent to the circle.
Tangential velocity is directly proportional to what?
The radius of the curve.
What is the distance travelled in one period with tangential velocity?
d=2 x pi x r
Explain the Law of Universal Gravitation between two objects in terms of proportionalities.
The Law of Universal Gravitation states that the force of attraction between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
Two students are sitting 1.50 m apart. One student has a mass of 70.0 kg and the other has a mass of 52.0 kg. What is the gravitational force between them?
1.08 × 10−7 N
The Law of Universal Gravitation states that “all objects are attracted to each other by a gravitational force. The strength of the force depends on the mass of each object and the distance between them.” According to this law, is there a stronger gravitational force between you and Earth or an elephant and Earth? Why?
A stronger gravitational force exists between the elephant and Earth because an elephant is more massive than a person. This creates a stronger gravitational force between the elephant and the Earth than there would be between a person and Earth.
True or false. As objects move, the force of gravity changes its direction to stay pointed along the line between their centers.
True.
Calculate the gravitational force between two objects when they are 7.50×10−1m apart. Each object has a mass of 5.00×101kg.
What gravitational force does the Moon produce on Earth if the centers of Earth, with a mass of 5.98×1024 kg, and Moon, with a mass of 7.35×1022 kg, are 3.84×108 m apart?
If the gravitational force between two objects of equal mass is 2.30×108N when the objects are 10.0m apart, what is the mass of each object?
Jupiter has the fastest rotation of all the planets in the Solar System, completing one rotation on its axis every 9.9 hours. The rapid rotation causes the planet’s equator to bulge out. Instead of being a perfect sphere, Jupiter looks more like a squashed ball. What is its angular velocity in radians per second?
What is the angular acceleration of a 12 cm music CD that begins at rest and accelerates to 50 rad/s in 1.217s?
When you whirl a rock at the end of a string it will follow a circular path. What will happen to the rock if the string breaks?
It will fly off in a straight line.
Which of the following best describes why objects can move in a circular path?
- The inertia of the objects pushes them along the circular path.
- A centripetal force pushes them toward the center of the circular path.
- The momentum of the objects pushes them along the circular path.
- A conduction force pushes them along the circular path.
A centripetal force pushes them toward the center of the circular path.
A race car is moving with a speed of 209km/hr on a circular section of a race track that has a radius of 300m. The car and driver have a combined mass of 788kg. What is the centripetal force acting on the car?
True or false.
If you were to whirl around a small weight attached to a string, and the string broke, the weight would fly off in a straight line away from the circle in the direction of and because of its tangential velocity.
True.
A wind turbine, with 4m long blades, turns at a rotor speed of 2.9rad/3s. What is the linear velocity of the tip of the blade?
