Physics Test 2

If y is inversely proportional to x^2, complete the following ratio Y1/Y2:

X2/X1

A car weighs 10,000N and has 300 horsepower. When moving at a constant speed, the net force on the car is:

Zero

A block has acceleration a when pulled by a string. If two identical blocks are glued together and pulled with twice the original force, what will their acceleration be?

a

The units that make up the newton are:

kg * m/s^2

An object at rest or in uniform motion in a straight line will remain that way forever, UNLESS

Acted upon by a net, external force

An object at rest or in uniform motion in a straight line will remain that way forever, unless

Acted upon by a net, external force

An object moves with a velocity that is constant in magnitude and direction, UNLESS

Acted upon by a nonzero net force

For a reaction to take place, the reactants must increase their potential energy by an amount. This is called...

Activation Energy

Something that acts or pushes or pulls

Agent (required for force)

Magnitude of supporting contact forces

Apparent Weight

Our feeling of supporting contact forces, as measured by an ordinary bathroom scale

Apparent weight

Suppose you are an astronaut in deep space, far from any source of gravity. You have two objects that look identical, but one has a large mass and the other a small mass. How can you tell the difference between the two?

Assuming you can exert a reproducible force in throwing both objects, you could throw each and note the acceleration each obtains.

A microscopic model for understanding the behavior and properties of macroscopic objects

Atomic Model

The figure below shows block A sitting on top of block B. A constant force F⃗ is exerted on block B, causing block B to accelerate to the right. Block A rides on block B without slipping.

Block B exerts a friction force on block A, directed to the right.

Dave pushes his four-year-old son Thomas across the snow on a sled. As Dave pushes, Thomas speeds up. Which statement is true?

Both forces have the same magnitude

Electric forces cause atoms to bind together to make molecules. This energy formed is called

Chemical Energy

The force of kinetic friction is calculated by multiplying the normal force on an object by the _______________ that is related to the surfaces involved

Coefficient of kinetic friction

The total energy of an isolated system is

Conserved

Forces that act on an object by touching it at a point of contact

Contact Forces

Energy is neither: (principle)

Created nor destroyed

Tennis balls experience a large drag force. A tennis ball is hit so that it goes up and then comes back straight down.

Down and then up

A person gives a box a shove so that it slides up a ramp, then reverses its motion and slides down. The direction of the force of friction is

Down the ramp and then up the ramp.

Scallops use jet propulsion to move from one place to another. Their shells make them denser than water, so they normally rest on the ocean floor. If a scallop wishes to remain stationary, hovering a fixed distance above the ocean floor, it must eject water _____ so that the thrust force on the scallop is _____.

Downward; Upward

A force that opposes or retards the motion of an object as it moves through a fluid (air/water)

Drag

A force that opposes or retards the motion of an object moving through a fluid

Drag

Force that opposes or resists motion when moving through fluids (like water/air) (opposite in direction)

Drag

An object moving in a straight line at constant speed is said to be in:

Dynamic Equilibrium

An object that is moving in a straight line at a constant speed

Dynamic Equilibrium

A weightlifter lifts a barbell over her head

E(chem) ---> U(g)

A burning campfire

E(chem) --> E(th)

Energy can be stored in a compressed or extended spring as

Elastic (or spring) potential energy

Energy stored when a spring or other elastic object is stretched

Elastic Potential Energy

Release less energy than was required to initiate it

Endothermic Reaction

A graph showing a system's potential energy and total energy as a function of position is called

Energy Diagram

An exchange of energy between the system and environment

Energy Transfer

If one form of energy in a system decreases, it must appear in an _____ amount in another form

Equal

The tension in a massless string or rope is ____________ the magnitude of the force pulling on the end of the string or rope

Equal

You're pushing horizontally on a large crate, but it won't budge. According to Newton's third law, the crate pushes back on you with the same magnitude of force that you exert on it. Suddenly the crate breaks free and you can now push it along the floor. Now is the force exerted on you by the crate greater than, equal to, or less than the force that you are exerting on the crate?

Equal

You're pushing a heavy filing cabinet across your office. You are tiring quickly and the cabinet is slowing down. The force that you exert on the cabinet is ______ the force that the cabinet exerts on you.

Equal To

When object A exerts a force on object B, object B exerts a force on object A that is

Equal and opposite to its force

If object 1 and object 2 interact, the force exerted by object 1 on object 2 is _________ in magnitude but ______________ in direction to the force exerted by object 2 on object 1

Equal; Opposite

Increase in thermal energy causes the final temperature of the products to be higher than the initial temperature of the reactants

Exothermic Reaction

Three arrows are shot horizontally. They have left the bow and are traveling parallel to the ground as shown in the figure. Air resistance is negligible. (Figure 1) Rank in order, from largest to smallest, the magnitudes of the horizontal forces F1, F2, and F3 acting on the arrows. Some may be equal. State your reasoning.

F1=F2=F3=0 because there is no change in the horizontal motion of the arrows.

(T/F) Astronauts in an orbiting space station are weightless because they are above the pull of gravity

False

(T/F) If Joe stands on a surface inclined at 10 degrees, the normal force on his feet will be more than his weight

False

(T/F) For every action, there is an equal but opposite reaction

False, this is only true regarding forces (when I take out money, money is not given back to me at the same rate/amount which I took it out at)

A push or a pull

Force

Acceleration is directly proportional to

Force

Something that is acting on an object

Force

The cause of motion

Force

Represents the object as a particle and shows all of the forces that act on the object

Free-Body Diagram

Force that is always parallel to the surface

Friction

Stored energy associated with an object's height above the ground

Gravitational Potential Energy

The higher the object is lifted, the greater ___________________________ in the object and earth system

Gravitational Potential Energy

The larger the displacement, the _______ the work done

Greater

The stronger the force, the ____________ the work done

Greater

A train engine pulls two identical cars behind it. Car 1 is attached directly to the engine, and car 2 is attached to car 1. The engine and cars are speeding up. The force of the engine on car 1 is _____ the force of car 1 on car 2.

Greater Than

Gravitational Potential Energy depends on the __________ of an object and not the path that the object took to get to that position

Height

A group of students is making model cars that will be propelled by model rocket engines. These engines provide a nearly constant thrust force. The cars are light-most of the weight comes from the rocket engine-and friction and drag are very small. As the engine fires, it uses fuel, so it is much lighter at the end of the run than at the start. A student ignites the engine in a car, and the car accelerates. As the fuel burns and the car continues to speed up, the magnitude of the acceleration will

Increase

A system that is separated from its surrounding environment in such a way that no energy is transferred into or out of the system

Isolated system

In the absence of friction, if a sled is moving,

It will stay in motion until acted upon

Jonathan accelerates away from a stop sign. His eight-year-old daughter sits in the passenger seat. On whom does the back of the seat exert a greater force?

Jonathan

The unit of all forms of energy

Joule (J)

A base runner slides into the base

K --> E(th)

If an object is sliding relative to the surface, what type of friction is occurring?

Kinetic

The energy of motion

Kinetic Energy

Acts as an object slides across a surface; "opposes the motion"

Kinetic Friction

Every particle in the Universe attracts every other particle with a force that is directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them

Law of Universal Gravitation

The magnitude of the drag force is proportional to the object's speed

Linear Drag

Forces that act on an object without physical contact

Long-Range Forces

A quantity that describes and object's inertia, its tendency to resist acceleration

Mass

Acceleration is inversely proportional to an object's

Mass

Weight is not the same thing as?

Mass

Are mass and weight the same thing?

NO!!!!

Is spring a constant?

NO!!!!!!

Represents a transfer of energy out of the system (type of work)

Negative Work

The vector sum of all of the forces

Net Force

The acceleration of an object is directly proportional to the __________ acting on it and inversely proportional to its _______

Net force; Mass (F=ma)

When your car accelerates away from a stop sign, you feel like you're being pushed back into your seat. Can you identify the force that is pushing you back?

No, there is no force pushing you backward, just the seat pushing forward.

The force exerted by a surface, perpendicular to the surface is called ________ force

Normal

An upward force that is directed in the opposite direction of the force

Normal Force

The forces that hold together the particles in the nucleus of the atom are much stronger than the electric forces that hold together molecules. When this bond breaks, it releases...

Nuclear Energy

A collision in which mechanical energy is conserved

Perfectly Elastic Collision

Only changes in ___________ energy are significant

Potential

Has the potential to be converted into other forms of energy

Potential Energy

The rate at which energy is transformed from one form into another

Power

All friction types (static, kinetic, rolling) does what?

Prevents motion

A force that opposes or resists motion

Resistive Force

Microscopic organisms that act against the action is known by

Reynolds Number

A number that is the ratio of the initial force to the viscous force

Reynolds Number (quadratic drag)

The tire of a moving bicycle experiences ______ friction

Rolling

If an object is rolling along the surface it is called...

Rolling Friction

The portion of the wheel that contacts the surface is stationary with respect to the surface, not sliding

Rolling Friction

Rotating about a fixed axis has:

Rotational Kinetic Energy

The pushing (when compressed) and pulling (when stretched) of...

Spring Force

The 2 categories of friction are:

Static & Kinetic

An object at rest is said to be in:

Static Equilibrium

An object in rest

Static Equilibrium

Keeps an object "stuck" on a surface and prevents its motion relative to the surface

Static Friction

Where does the vector for weight always point?

Straight down!

Josh and Taylor, standing face-to-face on frictionless ice, push off each other, causing each to slide backward. Josh is much bigger than Taylor. After the push, which of the two is moving faster?

Taylor will be moving faster.

When a string or rope wire pulls on an object

Tension Force

The steady, unchanging speed at which drag exactly counterbalances an applied force

Terminal Speed

The acceleration of an object is directly proportional to _______ and inversely proportional to _______

The object's net force

A baseball pitcher throws a 100 mph fastball to batter Brandon Bopp. Bopp hits a 450 foot home run out of the park. When the ball contacts the bat, which force was greater: the force of the ball on the bat or the force of the bat on the ball?

The two forces are the same.

The sum of all microscopic potential and kinetic energies is called

Thermal Energy

The sum of the microscopic kinetic and potential energies of all the molecules in an object

Thermal Energy

Suppose you are an astronaut on a spacewalk, far from any source of gravity. You find yourself floating alongside your spacecraft but 10 m away, with no propulsion system to get back to it. In your tool belt you have a hammer, a wrench, and a roll of duct tape. How can you get back to your spacecraft?

Throw the items away from the spaceship.

A force opposite the direction in which the exhaust gas is expelled

Thrust

Energy of one kind can be ____________________ into energy of another kind

Transformed

An object in motion moving along a line

Translational Kinetic Energy

A springboard diver

Us --> K --> U(g)

Force is a

Vector

Linear drag at low Reynolds number depends on the fluid's _____________

Viscosity

Striking a Match

W --> E(th)

Putting a shot (shotput)

W --> K

Firing a slingshot

W --> U(s)

Power is measured in

Watts

Another name for the force of gravity on an object at the Earth's surface:

Weight

The gravitational pull of the earth on an object on or near the surface of the earth

Weight

An object that is ________________ has no apparent weight

Weightless

An object pulled with a constant force moves...

With a constant acceleration

Energy transformations are changes of energy _________________ the system from one form to another

Within

What are the two main types of energy transfers

Work & Heat