### Angular Velocity & Acceleration Physics – Chapter 8

In this chapter we discuss angular velocity and acceleration physics – chapter 8

A generalization based upon experiments or observation.

**An empirical sceintific law**

An essential feature of a scientific theory is…

**The making of predictions that can be tested**

A meter is —– as long as a kilometer.

**1/1000**

A large ice cube is 30 cm on each side. If the length of each side is doubled, the surface area increases by a factor of…

**4**

A large ice cube is 30cm on each side. If the length of each side is tripled, the volume increases by a factor of…

**27**

1,000,000,000,000 bulls is equal to…

**Tbull**

10^-6 is equal to…

**(Mu)phone**

The radius of the earth is 6,380 km at the equator. It’s radius in scientific notation is…

**6.38×10^3 meters**

Which is faster, a person who can run 100 meters in 10 seconds or a person who can run 100 yards in 10 seconds?

**A person who can run at a speed of 10 meters per second**

Give an estimate of the number of steps in the stairway of a ten-story building.

**10^2**

Average speed is calculated by…

**Dividing the distance traveled by the elapsed time.**

Define acceleration.

**The change in velocity with respect to time.**

Velocity is what kind of quantity?

**A vector quantity**

Average speed during a very short time interval is…

**Instantaneous speed**

The slope of the distance traveled versus time graph is the…

**Velocity**

The slope of velocity versus time graph is the…

**Acceleration**

T/F: in the case of uniform accelerated motion, the graph of velocity versus time is a straight line.

**True**

T/F: in the case of uniform accelerated motion, the graph of distance traveled versus time is a straight line.

**False.**

T/F: if the acceleration is zero, the velocity is constant.

**True**

An object undergoing free fall experiences…

**A constant acceleration**

Just after it is released, an object thrown upward has… (in reference to its velocity and acceleration)

**It’s velocity directed upward and it’s acceleration directed downward**

Just before it reaches the peak of the path of its motion, an object thrown upward has… (in reference to its velocity and acceleration)

**It’s velocity directed upward and it’s acceleration directed downward**

After it passes the peak of the path of its motion, an object thrown upward has… (in regards to its velocity and acceleration)

**It’s velocity directed downward and it’s acceleration directed downward**

Who showed that in the absence of air resistance, all objects fall at the same rate regardless of their weight?

**Galileo**

Neglecting air resistance, a freely falling object has its velocity…

**Increase linearly with time**

Neglecting air resistance, a freely falling object has its displacement…

**Increase as the square of the time**

During every second after an object is dropped from rest and experiences free fall, it’s speed…

**Increases by 9.8 m/s**

Neglecting air resistance, one second after an object is dropped from rest and experiences free fall, it’s displacement is…

**4.9 meters**

Neglecting air resistance, one second after and object is dropped from rest and experiences free fall, it’s velocity is…

**9.8 m/s**

If no force is acting on an object, he object is…

**At rest or moving with a constant velocity**

According to newtons 2nd law, if the force is doubled and the mass remains the same, the acceleration…

**Will double**

An ice skater glides across a frozen pond at a constant velocity. What is the net force acting on the skater?

**Zero**

A single force is acting on an object. Which type of motion is not physically possible?

**The object is at rest**

If an astronaut takes an object to the moon what will happen to its weight and mass?

**The objects weight will change but it’s mass will be the same**

This force acts perpendicular to the surface.

**A normal force**

You stand on a scale that rests on the floor of an elevator that is accelerating upward. What is the relationship between the weight and the normal force exerted by the scale?

**The normal force is great than the weight**

A unit of force is…

**Newton**

Terminal velocity is a term used to describe…

**The constant velocity a falling object reaches when the net force is zero**

A bathroom scale with a person standing on it in an elevator accelerating downward would indicate…

**A smaller reading than if the elevator were at rest**

the center of all circular paths is defined as …..

**axis of rotation**

the angle through which an object rotates about a fixed axis

**angular displacement**

the angular displacement is hte angle ∆θ that is swept out by ……

**a line passing through any point on the body and intersecting at the axis of rotation perpendicularly**

by convention, the angular displacement is ______ if it is counterclockwise and ______ if it is clockwise

**positive if counterclockwise, negative**

angular displacement is often expressed in one of three units,

**1) degrees2) revolution3) radians (rad)**

θ in radians =

**arc length÷ radius (s/r)**

1 rad =

**360° / 2π = 57°**

Angular velocity describes the motion of…

**the motion of a rigid object rotating about a fixed axis**

average angular velocity (w) =

**angular displacement / elapsed time**

angular velocity unit:

**rad/s**

**changing angular velocity**

average angular acceleration =

**change in angular velocity / time**

angular acceleration unit:

**rad/s²**

a complete description for rotational motion requires values for the ____, ______, _____,_____and ______

**angular displacement ∆θangular acceleration αfinal angular velocity (w)initial angular velocity w₀and elapsed time ∆t**

when the angular acceleration is constant, the average angular velocity is given by :

**w = 1/2 (w₀ + w)**

tangential velocity

**vector drawn tangent to appropriate circle**

the tangential speed of any skater is directly proportional to the skater’s…

**distance R from the pivot**

the skater farthest from the pivot must have the largest….

**tangential acceleration**

the advantage to using angular velocity AND angular acceleration is that….

**these angular quantities describe the motion of the entire object**

in contrast with angular velocity and angular acceleration, the tangential velocity describe only …..

**the motion of a single point on the object**

when an object picks up speed as it moves around a circle, it has ______ ________

**tangential acceleration**

uniform circular motion

**object moves at a constant tangential speed on a circular path**

even when the magnitude of tangential velocity is constant, an acceleration is present, because

**the direction of the velocity changes continuously**

when the tangential speed is changing, the motion is called

**nonuniform circular motion**

the essence of rolling motion is that there is

**no slipping at the point of contact where the tire touches the ground**

when a rigid object rotates around a fixed axis, it is____ _______ that identifies the motion, and the angular velocity points along……

**the axis, this axis**

right hand rule

**grasp the axis of rotation with your right hand, so that your fingers circle the axis in the same sense as the rotation. your extended thumb points along the axis in the direction of the angular velocity vector**

no part of the rotating object moves in the direction of…..

**the angular velocity vector**

the acceleration vector has the same direction as the ________

**change in the angular velocity**

when the magnitude of the angular velocity (which is angular speed) is increasing, the angular acceleration vector points in the same direction as the _____

**angular velocity**