physics quiz questions

The other force in the action/reaction pair of a hammer striking a nail in a wall is

The force of the nail on the hammer

The net force on an object is

The vector sum of all the forces on the object

How are acceleration and force related?

Acceleration is directly proportional to force

A free body diagram should include

The object represented as a dot

All forces represented as vectors

A coordinate system

units of force

newton, (kg m)/sec², pound

If the net force on an object is zero, what can be said about the vectors on a free body diagram

The vector sum is zero

When a cat jumps from the floor onto a table, what can be said about the force on the floor

The force of the floor on the cat is equal to the force of the cat on the floor

An example of a long-range force is

weight

The net force on an object is

In the same direction as the acceleration

Newton’s 3^rd law says

All forces occur as a part of an action/reaction pair

The acceleration in the x-direction is determined by the

Sum of the x-components of all forces acting on the object

If an object is in equilibrium, what does Newton’s 2^nd law tell us?

The net force is zero.

The y component of an object’s acceleration is determined by

The y components of all the forces on the object

How can the apparent weight of on object be measured?

A simple scale

Riding in an elevator, when is your weight different than your apparent weight?

Any time an elevator’s speed is changing

What can be said about the net force on an object when its velocity is changing?

Net force is in the same direction as the acceleration.

An object in dynamic equilibrium is

Moving with a constant velocity

An object near the Earth seema ‘weightless’ if

it is in free fall

Is the net force larger when an object is in static equilibrium or dynamic equilibrium?

Net force for both is zero.

How are the mass (m) and weight (w) of an object related?

w=mg

Which of these does the kinetic frictional force not depend on?

Speed of the motion

Is the normal force affected by any other forces?

Yes, it is changed by forces that are parallel to the normal force.

Hook’s Law says the force of a spring

this is not in this chapter

The normal force on an object is always

Perpendicular to the surface the object is in contact with

The Reynolds number is used to characterize

The types of drag an object experiences

Terminal speed occurs when

The drag force is equal in magnitude to the weight

How does the coefficient of static friction usually compare to the coefficient of kinetic friction?

Static > kinetic

In order for a bicycle wheel to roll on the street the bottom of the wheel must

Be stationary

When trying to slide an object on a rough surface, what requires a larger force?

Getting it started

Drag on an object moving through a fluid depends on

Speed of the object

Viscous force of the fluid

Inertial force of the fluid

When analyzing an interaction involving three interacting objects how many free body diagrams need to be drawn?

3 – one for each object

When an object’s velocity is decreasing

The net force and the acceleration are opposite the motion

If the velocity of a moving object is not changing, then

The net force is zero

The kinetic frictional force is proportional to

The normal force on the object

How does a massless, frictionless pulley change the tension in a string?

Changes the direction of the tension

When two objects are connected by a string how are the tension forces on each object related?

The tension forces on each object are the same

The electric force of a proton on an electron

Is not in this chapter.

When objects are in contact with each other and moving together how are the accelerations of each object related?

They have the same acceleration

What approximations are made when dealing with pulleys and ropes in chapter 5?

The pulley is frictionless, and the pulley and string are both massless

Which of Newton’s laws are important for analyzing interacting objects?

The 2^nd and 3^rd laws

At what point on a roller coaster loop is your apparent weight the greatest

Bottom

The time for an object to complete one revolution is called the

Period

What is the force, F, needed to keep an object with mass m in a circular path with radius r at a constant speed v?

F = mv²/r

How are period (T) and frequency (f) in circular motion related?

T = 1/f

How does banking a curve on the highway allow cars to drive at a higher speed in the curve?

The normal force provides some centripetal acceleration.

The critical speed for traveling around a vertical loop

Depends on the radius of the loop

Is the speed at which the normal force is zero at the top

Is the slowest possible speed that can still complete the loop

The maximum safe speed to turn a corner depends on

The static friction between the tires and the road

According to the book, your maximum walking speed is determined by

The length of your leg

A car driving around a corner at a constant speed has

Acceleration toward the center of the curve

The centrifugal force

Is not an actual force

The speed of a satellite in a circular orbit around a star does not depend on

The mass of the satellite

Which of these is in free fall around the Earth?

All of these are in free fall.

The feeling of weightless near the Earth means

The object is in free fall

Two planets have the same mass, but planet X has twice the radius of planet Z. How does the acceleration due to gravity compare between the two?

Acceleration due to gravity is larger on Z

The period of a satellite orbiting a planet does not depend on

The mass of the satellite

A satellite is in a circular orbit around the Earth. What mass(es) does the orbital speed depend on?

Mass of the Earth only

Newton’s Law of Gravity says the gravitational force between two objects is related to the distance, r, between them as

1/r²

The acceleration due to gravity near the surface of the moon depends on

The mass and radius of the moon

As the distance between 2 objects increases, what happens to the force of gravity between them?

The force decreases.

An object in orbit around the Earth

Is in free fall

The critical speed for traveling around the inside of a vertical loop

Is the speed at which the normal force is zero at the top

Is the slowest possible speed that can still complete the loop

Depends on the radius of the loop

The centrifugal force

Is not a real force

The maximum safe speed to turn a corner depends on

The static friction between the tires and the road

How does banking a curve on the highway allow cars to drive at a higher speed in the curve?

The normal force provides some centripetal acceleration.

A satellite is in a circular orbit around the Earth. What mass(es) does the orbital speed depend on?

Mass of the Earth only

Newton’s Law of Gravity says the gravitational force between two objects is proportional to

1/r²

The period of a satellite orbiting a planet does not depend on

The mass of the satellite

Two planets have the same mass, but planet X has twice the radius of planet Z. How does the acceleration due to gravity compare between the two?

Acceleration due to gravity is larger on Z

The speed of a satellite in a circular orbit around a star does not depend on

The mass of the satellite

he acceleration due to gravity near the surface of the moon depends on

The mass and radius of the moon

Which situation creates the largest torque for the same amount of force

Long r with force perpendicular to radial line

The center of gravity of an extended object

Can be calculated from the center of gravity of individual pieces of the object

An object moving in uniform circular motion has

Constant angular velocity

Torque depends on

Angle of the applied force

Magnitude of the force applied

Distance, r, of applied force from pivot point

Tangential acceleration is equal to (α is angular acceleration)

α*r

Which is true for a rotating object (α is angular acceleration)?

a_cp > 0 even when α=0

If the center of gravity of an object is below its pivot point, the object will

Experience no torque

The unit for angular position used in this chapter is

Radians

Every point on a rotating rigid body has the same

Angular velocity

Angular velocity is positive for

counterclockwise rotation

Rolling motion

Depends on a momentarily stationary pivot point

Is a combination of linear and rotational motion

Has a different speed for each point on the object

Newton’s 2nd law for rotation says α is proportional to

τ_net

An object is connected to a string which goes over a pulley which has mass and a radius R. How is the acceleration of the object, a, related to the rotation of the pulley?

a = αR

A car is moving at 10 m/s. What is the speed of the point on the tire which is in contact with the road?

0 m/s

The moment of inertia of an extended object depends on

The shape of the object

Mass of the object

Location of the rotation axis

What is the rotational analog to mass?

I

What has the larger moment of inertia, a cylindrical disk or a cylindrical hoop? They have the same mass and radius.

Hoop

How does including the mass and radius of a pulley change the time for a bucket attached to a string going around a pulley to fall?

Increases the time for the bucket to fall

How are angular acceleration, α, and torque, τ, related for a single particle with mass m revolving at a distance r from the rotation axis?

α = τ/(mr²)

An object is connected to a string which goes over a pulley which has mass and a radius R. How is the speed of the object, v, related to the rotation of the pulley?

v = ωR

In order for an object to be in static equilibrium

Both the net force and the net torque equal zero

What factors contribute to improving the stability of an object?

Wider base and lower center of gravity

The spring force is

In the opposite direction as the change in the spring’s length

Hooke’s law relates

The spring force to the change in the length of the spring

For an object in static equilibrium

The net torque about any point is zero

For a particular spring, the spring constant

Is the same regardless of stretching or compressing

Which object produces a restoring force?

Rubber band

Spring

Leg bone

Steel beam

An object can remain balanced if

Its center of gravity is over the pivot point