Studied by 8 people
Angular displacement
The angle of the movement of a body in a circular path
Angular speed
The rate of change of angular displacement
Angular acceleration
The time rate of change of angular velocity
Torque
The measure of the force that can cause an object to rotate about an axis
Force
The push or pull on an object with mass causes it to change its velocity.
Linear acceleration
The uniform acceleration caused by a moving body in a straight line
Balanced forces
Forces that are equal in magnitude but opposite in direction
Balanced torques
The size and direction of the torques acting on an object are exactly balanced
Axis of rotation
The straight line through all fixed points of a rotating rigid body around which all other points of the body move in circles
Center of gravity
The average location of the weight of an object
Rotational mass
A description of how easy or difficult it is to rotate a body or to stop it once it is rotating
Mass
The measure of the amount of matter in an object
Parallel forces
Forces that lie in the same plane and have lines of action that never intersect each other
Law of conservation of angular momentum
When angular momentum is conserved when there is zero net torque applied to a system, where the system is the object or objects that are rotating
Gyroscope
A device used for measuring or maintaining orientation and angular velocity
Precession
The change in orientation of the rotational axis of a rotating body
Topple
To fall because of overbalance
Stability
The ability of an object to maintain its balance after being disturbed
1st and 2nd condition of equilibrium
Firstly, the net force acting upon the object must be zero. Secondly, the net torque acting upon the object must also be zero
Rotational inertia
A property of any object which can be rotated
Moment of inertia
Quantitative measure of the rotational inertia of a body
Forces make objects accelerate in a straight line (linearly) torques make objects ___?___.
accelerate angularly (increase rotational speed)
An angle of ___?___ between the force and the lever arm gives a maximum torque.
90 degrees
Torque is calculated by ___?___ the ___?___ with the ___?___ as described in the equation ___?___.
multiplying, force, lever-arm, T = F x l
Torque can have a direction of ___?___ or ___?___.
clockwise, counterclockwise
An object like a seesaw is balanced when ___?___ and ___?___ are balanced.
forces, torques
C.O.G. is the abbreviation for ___?___.
center of gravity
Two objects whose c.o.g. is located where no material exists are ___?___ .
answers will vary (boomerang, hoop)
An object will topple if its c.o.g is located outside of its ___?___.
base
An object is most stable when its ___?___ is located at the ___?___ possible point.
cog, lowest
You can increase your bodies stability by moving your feet ___?___.
apart
An object at rest stays at rest and an object in motion stays in motion describes the property of matter called ___?___.
inertia
Objects that are rotating have ___?___ inertia.
rotational
If the mass of a body is located close to its axis of rotation, it is ___?___ to rotate the body because it has a ___?___ rotational mass.
easy, low
A ___?___ pendulum is more difficult to rotate and therefore swings more slowly.
long
Animals with shorter legs have ___?___ strides than long-legged animals because their legs have ___?___ rotational masses.
quicker, less
The formula for angular momentum is ___?___.
L = Iω
If you are rotating on an office chair with your arms and legs extended and you pull them inward your:
a. Rotational speed will ___?___
b. Angular momentum will ___?___
c. Rotational mass will ___?___
d. Angular acceleration will ___?___
a. Increase
b. Stay the same
c. Decrease
d. Increase
A gymnast tucks to make a somersault. Her rotational mass decreases during the tuck. Her ___?___ is conserved because her ___?___ increases during the tuck.
angular momentum, rotational speed
The angular momentum before a somersault is equal to the ___?___ after the somersault.
angular momentum
A spinning bicycle wheel does not easily fall over because it behaves like a ___?___ which has the characteristic of always keeping its axis pointed in the same direction.
gyroscope
The symbols that represent angular distance, angular speed, and angular acceleration respectively are ___?___, ___?___, & ___?___.
Δ, θ, ω, α
When a rotating body increases angular speed, it is said to be undergoing ___?___.
angular acceleration
Torque is the ___?___ effect of a force about an axis.
twisting
Torque is found by the product of ___?___ and ___?___.
force, lever-arm
Two ways of increasing torque are ___?___ force or ___?___ the lever arm.
increasing, increasing
The point that a rotating body spins about is called ___?___.
axis of rotation
The point where all mass of a body may be considered to be concentrated is its ___?___.
cog
List three characteristics of the center of gravity.
a. not always within the object
b. always tries to reach the lowest possible position
c. natural axis of rotation
The stability of an object can be increased by ___?___ the cog or by ___?___ its base.
lowering, widening
When the mass is concentrated far from the axis of rotation, the body has ___?___ rotational mass.
high
The angular acceleration will increase if the torque applied to a rotating body ___?___ or if the rotational mass of the body ___?___.
increases, decreases
When a skater increases her rotational mass, her angular speed ___?___ to conserve angular momentum.
decreases
A body rotating about an axis is called a ___?___.
gyroscope
___?___ occurs when a force tries to change the direction of the ___?___ of rotation of the gyroscope.
Precession, axis
How far can a body be tipped before it topples over?
Until the cog is outside of the base or support of the object.
Why doesn’t the Leaning Tower of Pisa topple over?
Its cog is within its base.
Why must you bend forward when carrying a heavy load in your backpack?
The backpack shifts your cog outside of your heels so you bend forward to shift it back over your feet (base).
Why is it easier to carry the same amount of water in two buckets, one in each hand, than in a single bucket?
It is the same weight but the torque is harder to balance with only one bucket compared to two.
How can three bricks be stacked so that the top brick has maximum horizontal displacement from the base of the bottom brick?
First brick out a ¼, second brick out ½.
Nobody at the playground wants to play with the obnoxious boy, so he fashions a seesaw out of a plank of wood and a rock that he can play with by himself. Explain how this can be done. 7. One 50 gram rock is balanced on a meter-stick with a fulcrum at 25 cm. The rock is at the 0 cm mark. What is the mass of the meter-stick?
He can balance the torques using the weight of the bar instead of another child. He must put the bar off-center for this to be possible.
