Circular Motion Basics
What does it mean for an object to move in a circle at constant speed?
The object moves at a constant speed but continuously changes direction.
What is the name of the force that keeps an object moving in a circle?
Centripetal force.
What does Newton’s Law of Universal Gravitation state?
Every mass attracts every other mass with a force proportional to their masses and inversely proportional to the square of the distance between them.
What force provides the centripetal force for satellites in orbit?
Gravitational force.
What is the formula for centripetal acceleration?
a=v2/r
How is velocity changing during uniform circular motion?
Velocity is constantly changing because its direction changes, even if speed stays the same.
What type of force provides centripetal force for a satellite orbiting Earth?
Gravitational force.
What two factors affect the strength of gravitational force?
Mass and distance.
Why don’t satellites need engines to stay in orbit?
Their forward velocity combined with gravity causes them to continuously fall around Earth instead of straight down.
What is the formula for centripetal force?
F=mv2/r
Why is an object accelerating even if its speed is constant in circular motion?
The object is accelerating because acceleration depends on changes in velocity, and the direction is changing.
What does the free body diagram look like for a ball on a string moving in a horizontal circle?
The free body diagram shows tension pulling inward toward the center, with no outward force.
How does gravitational force change if the distance between two objects doubles?
The gravitational force becomes one-fourth as strong.
How does orbital speed change as a satellite moves closer to Earth?
Orbital speed increases.
What is the centripetal acceleration of an object moving at 10 m/s in a 5 m radius circle?
20 m/s2
What direction does centripetal acceleration point during circular motion?
Centripetal acceleration always points toward the center of the circular path.
How does the direction of the net force compare to the direction of velocity in circular motion?
The net force points toward the center, while velocity is tangent to the circle.
What is the equation for gravitational force, and what do the variables represent?
F=G(m1m2/r2)
F=Gravitational force G= Grav constant m1=mass obj 1, m2=mass obj 2, r=radius
How are gravitational force and centripetal force related for a satellite in circular orbit?
Gravitational force is the centripetal force that causes the circular motion.
What provides the net force acting on a satellite in circular orbit?
Gravitational Force
A car moves around a circular track at constant speed. Describe its speed, velocity, and acceleration.
Speed is constant, velocity is changing direction, and acceleration is directed inward toward the center.
What forces act on a satellite in circular orbit, and why doesn’t it fly off into space?
The free body diagram shows only gravitational force acting inward, which provides the centripetal force that keeps the satellite in orbit.
Two planets have the same mass, but Planet A is twice as far away. How does the gravitational force compare?
Planet A experiences one-fourth the gravitational force.
If a satellite’s speed increases but its orbital radius stays the same, what happens to the required centripetal force?
The centripetal force must increase.
Why does increasing speed require a much larger centripetal force?
Because centripetal force is proportional to the square of velocity.