Physics: Forces, Work, Energy, and Fluid Mechanics Concepts

Friction will always act in the direction....

opposing motion or attempted motion between surfaces

Which of the following is the magnitude of the universal gravitational constant

6.67e-11

Which is true of centripetal force in uniform circular motion?

it is directly proportional to mass and inversely proportional to radius

When is positive work done?

force and displacement are in the same direction.

If the object is at the lowest point (h = 0),

the gravitational potential energy at that point is zero

When is negative work done?

parallel, but opposes motion of the object

At which point is atmospheric pressure greatest

none of the above

Water is flowing from left to right through the tube. Which pressure guage shows the highest pressure?

3

Which of the following is true for a closed container?

absolute pressure is proportional to h where h is the depth within a fluid

A sprayer head is attached to a garden hose. The area of the sprayer head outlet is S & the area of the hose outlet is H. If the diameter of the sprayer head outlet is increased by a factor of 3, water velocity will.

decrease by a factor of 9

pressure

force per unit area

A large sphere of lead is thrown into a river where it sinks to the bottom. When is the buoyant force greatest?

when it is completely submerged

In terms of forces, why is this bird floating on the water?

buoyant force is equal to the force of gravity acting on the bird

When submerged in the tank, the ball is held in place by the string attached to the bottom of the tank with nonzero tension. Which is true?

The fact that there is tension in the string is evidence that the density of the cube is less than the density of the fluid.

Water is flowing from left to right through the tube. Which section has the greatest volume flow rate?

they are all the same

As the speed of a fluid increases, ____.

the pressure decreases

lift

an upward force

Water is flowing from left to right through the tube. Which section has the highest velocity?

2

In all cases, the buyoant force exerted on an object in a fluid, whether floating or submerged, is equal to

the weight of the fluid displaced

Where is gauge pressure greatest?

the bottom of a container

The buoyant force on an object in a fluid is equal to

submerged volume of the object density of the liquid g

In order to calculate pressure exerted on a surface, what quantity is divided by the surface area?

force

The buoyant force on an object is in the _____ direction.

upward

The upward force acting on an object by a fluid is called

buoyant force

Density

Mass per unit volume

If an object sinks in a fluid, the buoyant force is ____ the weight of the object.

less than

If an object sinks in a fluid, the buoyant force is ____ the weight of the object.

less than

A car has a mass v and a velocity v. A truck that has 2m and 2v. What is the ratio of the car's momentum to the truck's momentum?

1/4

A person pushes on a wall, but the wall does not move. Is there work done on the wall?

No

What happens when the static friction reaches its max?

The object begins to move

What does the area under this graph represent

Inpulse

At the location of the ball, which arrow represents the velocity?

2

Which set of photos shows no acceleration?

Middle

Which set of photos shows a positive acceleration?

Bottom

Which set of photos shows a negative acceleration?

Top

Define friction

force that opposes sliding

An ice skater spins on frictionless ice with her arms spread out then brings them inward, changing her rotational speed. This situation best exemplifies which of the following?

conservation of angular momentum

An ice skater spins on frictionless ice. What happens when she brings her arms in closer to her body?

her rotational inertia decreases & her rotational speed increases

Increasing the time of a collision has what effect?

reduces impact force

What is conserved in an inelastic collision? [objects stick together]

momentum only

Work is a _______ quantity but it can be positive or negative.

scalar

Equation for weight

Fg = m*g

Normal Force

the contact force applied to an object, always perpendicular to the surface

Newton's second law could be written as T = I α

true

The period of a pendulum can be decreased by which of the following methods?

Decreasing the length of the pendulum

As a car moves down the road, what do its tires encounter from the surface of the road?

static friction

Which of these is not doing work?

Holding a ball

energy

all of these

potential energy

energy stored due to positions of objects within a system

number that tells you how easily an object will deform

spring constant

When a plane hits a Godzilla head on, who experiences the least amount of force?

They experience the same force

When is kinetic energy NOT conserved?

inelastic collisions

During which time interval does the greatest impulse occur?

2-4 seconds

This car is

slowing down & turning counterclockwise

These train cars are connected by metal bars. Masses and forces are shown. The engine accelerates at 2 m/s^2 & friction is negligible. Which force is the greatest?

F1

Which statement about friction is true?

friction decreases mechanical energy

For round objects rolling on an incline, the faster objects are generally those with the

lowest rotational inertia

What happens to the value of g as you move away from the Earth's surface?

it decreases as 1 / r^2

What is the unit for torque?

N m

What is the unit for angular momentum? (L = mvr)

kg m^2 /s

Suppose you try loosening a nut and it doesn't rotate at all. You can increase success if you

Use a longer wrench

exert a larger force

be sure to exert force perpendicular to the wrench

If two ladybugs are on the spinning disk, which will have a greater angular speed?

They have same angular speed

The instantaneous velocity and acceleration of an object moving in a circle are

perpendicular

angular velocity

how fast an object rotates or revolves relative to another point

The resistance an object has to changes in its rotational motion is called rotational

inertia

1 revolution

360 degrees

tangential speed is given by

v = ωr

Angular momentum can be written as

L = I ω

Centripetal force is given by

F = mω^2r

1 revolution

2π radians

angular velocity

Angular displacement divided by the time.

angular acceleration

Change in angular velocity divided by the time required to make that change.

An angle in radians is given by...

arc length / radius

Define friction

force that opposes motion

Balanced causes an object to stay at rest or stay in a straight line constant velocity is :

Newton's 1st Law

How much work is done is circular motion?

0

What is conserved in an elastic collision?

both kinetic energy and momentum

Change in momentum is equal to:

Impulse

momentum is

mass with velocity

An unbalanced force causes acceleration is:

Newton's 2nd Law

If the net work done is negative, the kinetic energy:

decreases

What is conserved in an elastic collision?

momentum & kinetic energy

If the net work done is negative, the kinetic energy:

decreases

An object is whirled around on a string in a vertical circle at a constant speed. At which point of its path is the tensional force the least and why?

at the top (because gravity acts downward in the same direction as Fc, reducing the required tension for constant speed)

An object is experiencing a non-zero net force. What's happening?

the object is accelerating

This free body diagram could represent which of these situations?

a box being pulled by a rope on a frictionless surface & accelerating

An object is at rest on an inclined surface. The force that keeps the object at rest is

static friction

An object is at rest on an inclined surface. The normal force on the object is equal to

the component of the object's weight that is perpendicular to the surface

A student pulls a block over a rough surface with a constant force FP that is at an angle θ above the horizontal, as shown. If FP remains constant but the angle θ is increased, which of the following is true?

The force of friction between the block and surface will decrease.

A block of mass M is attached to a modified Atwood machine and is accelerated upward at 3a by a constant force F0. What is the weight of the block?

Mg

The area under the curve of a v-t graph equals

displacement

The slope of an x-t graph tells you

velocity

The object that made this graph is

accelerating in a positive direction

An object is whirled around on a string in a vertical circle at a constant speed. At which point of its path is the tensional force the greatest?

at the bottom

A 10 kg object is thrown straight up with a kinetic energy of 400 J. How high will it rise?

4 m

What is the y-component of velocity at the top of the trajectory of a projectile?

0

What happens to the x-component of velocity for a projectile during its trajectory? (ignore air resistance)

remains constant

What is an object doing when the velocity is negative and the acceleration is positive ?

slowing down

When answering an FRQ question...

Address every variable. Even if they are constant