Centripetal means acting towards the centre of a circular path.

Define uniform circular motion .

Motion in a circle at a constant linear speed , with continuously changing direction (and therefore velocity).

Why is an object in uniform circular motion accelerating, even though its speed is constant?

Velocity is a vector, so its continuously changing direction means velocity is changing; acceleration is the rate of change of velocity.

What is the direction of the centripetal acceleration relative to the linear (tangential) speed?

Perpendicular to the linear speed, directed towards the centre of the circle.

What causes the centripetal acceleration of an object moving in a circle?

A centripetal force of constant magnitude, acting perpendicular to the direction of motion (towards the centre) — a result of Newton's second law .

The centripetal force and centripetal acceleration always act in the .......... direction.

The centripetal force and centripetal acceleration always act in the same direction.

True or False? The tangent to a circle at a point always acts parallel to the radius at that point.

False. The tangent to a circle always acts perpendicular to the radius, not parallel to it. Linear speed is therefore sometimes called ‘ tangential ’ speed.

The angle subtended at the centre of a circle by an arc equal in length to the radius of the circle.

In circular motion, angular displacement is measured in .......... rather than degrees, as this is more convenient.

In circular motion, angular displacement is measured in radians rather than degrees, as this is more convenient.

True or False? To convert an angle from degrees to radians, you multiply by 180/π.

False. To convert from degrees to radians, multiply by π/180 . Multiplying by 180/π converts from radians to degrees .

Define angular speed .

The rate of change of angular displacement with respect to time.

For a given linear speed, an object rotating further from the centre of a circle (larger radius) has a .......... angular speed.

For a given linear speed, an object rotating further from the centre of a circle (larger radius) has a smaller angular speed.

True or False? Angular speed and angular velocity are the same thing.

False. Angular speed is a scalar quantity, whereas angular velocity is the equivalent vector quantity.

Define centripetal acceleration .

The acceleration of an object towards the centre of a circle, when the object moves around the circle at a constant speed.

Centripetal acceleration is always directed .......... the centre of the circle, and is perpendicular to the object's velocity.

Centripetal acceleration is always directed towards the centre of the circle, and is perpendicular to the object's velocity.

True or False? Centripetal acceleration acts in the same direction as an object's linear velocity.

False. Centripetal acceleration always acts perpendicular to the object's velocity, directed towards the centre of the circle.

Define centripetal force .

The resultant force towards the centre of a circle required to keep a body in uniform circular motion; it is always directed towards the centre of the body's rotation.

Is centripetal force a separate, distinct type of force?

No — it is not a separate force of its own; it can be any type of force (for example tension , gravity or friction ) that acts to keep an object moving in a circular path.

Why is no work done on an object travelling in uniform circular motion?

The centripetal force is always perpendicular to the direction of travel, so it does no work and there is no change in kinetic energy .

Centripetal force and centripetal acceleration always act in the .......... direction, as a result of Newton's second law.

Centripetal force and centripetal acceleration always act in the same direction, as a result of Newton's second law.

True or False? Centripetal force does work on an object moving in uniform circular motion, increasing its kinetic energy.

False. Centripetal force is always perpendicular to the direction of travel, so it does no work and there is no change in kinetic energy .

A LevelPhysicsAQAFlashcardsFurther Mechanics & Thermal PhysicsCircular Motion

Circular Motion (AQA A Level Physics): Flashcards

Exam code: 7408

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Define centripetal.

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Cards in this collection (34)

Define centripetal.
Centripetal means acting towards the centre of a circular path.
Define uniform circular motion.
Motion in a circle at a constant linear speed, with continuously changing direction (and therefore velocity).
Why is an object in uniform circular motion accelerating, even though its speed is constant?
Velocity is a vector, so its continuously changing direction means velocity is changing; acceleration is the rate of change of velocity.
What is the direction of the centripetal acceleration relative to the linear (tangential) speed?
Perpendicular to the linear speed, directed towards the centre of the circle.
What causes the centripetal acceleration of an object moving in a circle?
A centripetal force of constant magnitude, acting perpendicular to the direction of motion (towards the centre) — a result of Newton's second law.
The centripetal force and centripetal acceleration always act in the .......... direction.
The centripetal force and centripetal acceleration always act in the same direction.
True or False?
The tangent to a circle at a point always acts parallel to the radius at that point.
False.
The tangent to a circle always acts perpendicular to the radius, not parallel to it. Linear speed is therefore sometimes called ‘tangential’ speed.
Define angular displacement.
The change in angle, in radians, of a body as it rotates around a circle: $Δ θ = \frac{s}{r}$ (arc length divided by radius).
Define radian.
The angle subtended at the centre of a circle by an arc equal in length to the radius of the circle.
What is the angular displacement, in radians, of one complete circle (360°)?
$2 π$ radians.
Write the equation used to convert an angle from radians to degrees.
$θ rads \times \frac{180}{π} = θ °$
Write the equation used to convert an angle from degrees to radians.
$θ ° \times \frac{π}{180} = θ rads$
In circular motion, angular displacement is measured in .......... rather than degrees, as this is more convenient.
In circular motion, angular displacement is measured in radians rather than degrees, as this is more convenient.
True or False?
To convert an angle from degrees to radians, you multiply by 180/π.
False.
To convert from degrees to radians, multiply by π/180. Multiplying by 180/π converts from radians to degrees.
Define angular speed.
The rate of change of angular displacement with respect to time.
What are the SI units of angular speed?
rad s^-1
Write the equation for angular speed in terms of angular displacement and time.
$ω = \frac{Δ θ}{Δ t}$
Write the equation for angular speed in terms of the time period T and frequency f.
$ω = \frac{2 π}{T} = 2 π f$
Write the equation relating angular speed ω to linear speed v and radius r.
$ω = \frac{v}{r}$
For a given linear speed, an object rotating further from the centre of a circle (larger radius) has a .......... angular speed.
For a given linear speed, an object rotating further from the centre of a circle (larger radius) has a smaller angular speed.
True or False?
Angular speed and angular velocity are the same thing.
False.
Angular speed is a scalar quantity, whereas angular velocity is the equivalent vector quantity.
Define centripetal acceleration.
The acceleration of an object towards the centre of a circle, when the object moves around the circle at a constant speed.
Write the equation for centripetal acceleration in terms of linear speed v and radius r.
$a = \frac{v^{2}}{r}$
Write the equation for centripetal acceleration in terms of radius r and angular speed ω.
$a = r ω^{2}$
Write the equation for centripetal acceleration in terms of linear speed v and angular speed ω.
$a = v ω$
Centripetal acceleration is always directed .......... the centre of the circle, and is perpendicular to the object's velocity.
Centripetal acceleration is always directed towards the centre of the circle, and is perpendicular to the object's velocity.
True or False?
Centripetal acceleration acts in the same direction as an object's linear velocity.
False.
Centripetal acceleration always acts perpendicular to the object's velocity, directed towards the centre of the circle.
Define centripetal force.
The resultant force towards the centre of a circle required to keep a body in uniform circular motion; it is always directed towards the centre of the body's rotation.
Write the equation for centripetal force in terms of mass m, linear speed v and radius r.
$F = \frac{m v^{2}}{r}$
Write the equation for centripetal force in terms of mass m, radius r and angular speed ω.
$F = m r ω^{2}$
Is centripetal force a separate, distinct type of force?
No — it is not a separate force of its own; it can be any type of force (for example tension, gravity or friction) that acts to keep an object moving in a circular path.
Why is no work done on an object travelling in uniform circular motion?
The centripetal force is always perpendicular to the direction of travel, so it does no work and there is no change in kinetic energy.
Centripetal force and centripetal acceleration always act in the .......... direction, as a result of Newton's second law.
Centripetal force and centripetal acceleration always act in the same direction, as a result of Newton's second law.
True or False?
Centripetal force does work on an object moving in uniform circular motion, increasing its kinetic energy.
False.
Centripetal force is always perpendicular to the direction of travel, so it does no work and there is no change in kinetic energy.

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