Physics Final

Which of the following is a unit of work?

Joule

In theoretical physics. an ideal spring

has a nearly constant spring constant, k

the force it takes to stretch a spring

is in the opposite direction to the force exerted by the spring

the SI unit of power is

watt

which statement is true about he work energy theorem

it states that the work done on an object is equal to the change in the object's kinetic energy

A book is lifted up from the floor and put on a shelf with a height, h .

Delta U\= |mg| h

Peter knocks a book off the 0.9 m-high table and it falls to the floor. Karin picks it up and places it pack on the table. What is the total change in the gravitational potential energy of the book?

ΔUg \= 0 J

The formula U\=|mg| h

gravitational potential energy

When potential energy of a system is zero and its total mechanical energy is a nonzero. then

the system is in motion

Work is scalar or vector?

scalar

Work

w\=Fdcosθ

1 Joule

1 nm

Energy

the ability to do work

work and energy have the same units

Joules

Is it possible to exert a large force on a system and yet do no work

Yes

Equilibrium position

The reference position for a spring's motion

Power is scalar or vector

scalar

Will a compressed spring have more energy than any other kind of energy

No

A falling object can have both potential and kinetic energy

Yes

Total mechanical energy

the sum of kinetic and potential energy

Jon pushes a lawnmower with a force of 50.0N directed at 50° from the horizontal. The total distance the lawnmower moves is 90.0m. How much work did Jon do with the lawnmower?

2892.54 Joules

Jon pushes a lawnmower with a force of 45.0N directed at 40° from the horizontal. If Jon took 1 hour to mow 75.0 m of grass, what was his power in SI units?

0.7181 Watts or 7.18 x 10^1

Chucl weighs himself on a bathroom scale containing a heavy spring which has a constant of 5.0 x 10^2 N/m. The spring is compressed 1.25 cm under his weight. Find the total work done on the spring during the compression.

Wspring\= 0.03906 Joules

A farmer uses a hay bale conveyor to load hay into the hay loft of his barn. If the height of the conveyor belt is 6.7m, what is the change in potential energy of 23 kg bale of hay from the ground to the loft?

U\= 1511.721 Joules

Bob is riding on a roller coaster. He begins heading down a hill and reaches a speed of 30 m/s Bob and the cart no have a total kinetic energy output of 2025000 Joules. What is the combined mass of the Bob and the cart?

4500kg

The SI unit of force is the

newton

Which is an example of a system on which unbalanced forces act?

A child sliding down a waterslide

The force that acts with one or more other forces to produce mechanical equilibrium is called the

Equilibrant

Which statement represents completely balanced forces

ΣF\=0

Weight is

a force

An example of a system in which unbalanced forces are at work is

a child sliding down a slide

Pinching one's fingers uses what kind of contact force?

Compression

Air resistance is what kind of contact force?

Friction

When you pulled a glazed sheet of paper from underneath a neatly stacked pile of coins, the coins remain stacked afterward. Which of the Newton's three laws does this exhibit?

First law

What happens when all the external forces on a system are balanced?

the velocity is constant

Without unbalanced forces, moving objects will

move in straight lines

When you push on a heavy, immovable boulder, the boulder also pushes on you. This is an example of which of Newton's laws?

Third Law

The kick from the firing of a high-powered rifle illustrates which of Newton's laws?

Third law

Acceleration can be calculated from

dividing a resultant force by mass.

A force of 20.0N gives an object an acceleration of 12.5 m/s^2. What is the mass of the object

1.60 kg

What is not one of the properties of force due to the third law?

If the resultant force is zero, the acceleration is zero

What is not a contact force

gravity

The SI unit of mass is the

kilogram

T/F: In the absence of air resistance, all objects fall at the same rate

True

T/F: The tendency to resist a change in motion is inertia

True

T/F: Forces do not always cause a change in motion

True

T/F: The force of gravity acting on an object is its mass

False

T/F: Newton's first law of motion predicts that without unbalanced forces, moving objects will travel in straight lines.

True

T/F: An object is in mechanical equilibrium when the sum of the applied forces is zero

True

T/F: Mass determines an object's inertia

True

T/F: Forces can occur only in pairs

True

T/F: The weight of an object on Pluto is the same as its weight on Earth

False

T/F: The mass of an object on Pluto would be the same as its mass on Earth

True

T/F: The weight vector points in the same direction as the gravity vector

True

T/F: If the mass of an object is doubled under a constant force, its acceleration is doubled

False

A vertical fishing line supports an 8.0 kg fish when it is held up for a picture of the "big one" What force is exerted on the fishing line?

F\= -78.48N down

An aircraft is landing on an aircraft carrier. The aircraft's mass is 17,600kg. Assuming its initial horizontal landing speed is 66 m/s, what is the magnitude of the force that the arresting wire exerts on the aircraft, assuming that the aircraft's deceleration is uniform?

725000 N

What force must a car's engine and tires exert on the ground in order to accelerate it at 6.89 m/s^2, assuming that the vehicle has a mass of 1330 kg?

F\=9163.7N

Two linemen on opposing football teams are pushing aginst each other during a game. Lineman A is pushing with a force 7000N of force. Lineman B pushes back with 6800N of force. Who wins and how much excess force is generated

F\=200N; Lineman A wins

Bob is riding in an elevator that weighs 1520kg. Bob weighs 80kg. In order for the elevator to descend without injuring him, there is a counterweight attached to a rope with a mass of 1450 kg. Find the tension force (Ft) and the acceleration rate (a) of the elevator as it descends

Acceleration rate\= -0.48m/s

Tension Force\=1471.5N

Speed is scalar or vector

scalar

Displacement must always be measured from

reference point

The slope of a two-dimensional position-time graph gives

velocity

On a position-time graph, the average velocity between two points is

computed by a change in position divided by change in time between the two positions

the speedometer on your car measures

instantaneous speed

T/F: Kinematics explains the causes of motion

False

T/F: Motion is the change of position during an interval of time

True

T/F: The magnitude of a dimensional quantity is a scalar

True

T/F: Vector measurements identify only the quantity aspect of motion, whereas scalar measurements identify both the quantity and the direction involved in motion

False

T/F: Displacement is the distance between an object's initial and final positions during a given time interval.

False

T/F: Average acceleration is the change in velocity over a given interval of time.

True

T/F: If an object's speed is constant, then acceleration is zero.

False

T/F: An object that is slowing in the positive direction would be experiencing a deceleration

True

A runner takes 45.4s to run a 400-meter run (400.0 m). What is his average speed?

Average Velocity\= 8.81m/s

From a rest position, a car reaches a velocity of 50.0 km/h in 15.0s at a constant rate of acceleration. What is the acceleration in m/s^2

a\=0.926m/s^2

An airplane taxing toward the runway at a speed of 15.0 m/s starts accelerating at a constant rate of 3.20 m/s^2. How long will it take the plane to reach 45.0 m/s\>

t\= 9.375s

What does ΔT mean?

t2-t1

A bicyclist passing through a city accelerates after he passes the signpost marking the city limits. His acceleration is constant at 6.0 m/s^2. At time t1\= 0s, he is at x1\= 7.0 m beyond the signpost and has a velocity v1\= 5.0 m/s. Find his position (distance from the signpost) 3 s after passing the signpost (at t\= 3.0s)

Pf \= 49m

A bicyclist passing through a city accelerates after he passes the signpost marking the city limits. His acceleration is constant at 6.0 m/s^2. At time t1\= 0, he is at x1\= 7.0m beyond the signpost and has a velocity v1\= 5.0 m/s. Find his velocity at t\= 3.0s

Vf \= 23m/s

A bicyclist passing through a city accelerates after he passes the signpost marking the city limits at x\= His acceleration is constant at m/s^2 east. At time t 1\= 0.0s, he is located at x1\= 6.0 m and has a velocity v1\= 4.0 m/s east. Find his position and velocity at t2\=2.0s

Pf \= 24m, Vf \= 14m/s

A bicyclist passing through a city accelerates after he passes the signpost marking the city limits at x\= His acceleration is constant at 5.0m/s^2 east. At time t1\= 0.0s, he is located at x1\= 6.0 m and has a velocity v1 \= 4.0 m/s east, How far is he from the signpost when his velocity is 6.0 m/s?

d \= 8.0m

A student is pedaling his bike to class at a leisurely pace of v \= 1.50 m/s. Then he looks down at his watch and realizes that he has 2.00 minutes to get to class and he is still 1.0 km away. He starts accelerating at a uniform of 0.100 m/s^2. If he is able to maintain his acceleration until he gets to school, does he make it to class on time?

d2x \= 900m; With his inital speed and acceleration, he cannot travel the remaining distance fast enough to make it to class in the two remaining minutes.

A student is pedaling his bike to class at a leisurely pace of v \= 1.50 m/s. Then he looks down at his watch and realizes that he has 2.00 minutes to get to class and he is still 1.0 km away. He starts to accelerate at a uniform 0.100 m/s^2. How fast is the student going when he arrives at the school?

V2x \= 14.22 m/s

Fundamental dimension

Space, time, matter

The physical universe consists of space, time, and

matter

The length of a book should be most appropriately measured in

centimeters

What is the SI unit for mass?

Kilogram

What is the appropriate conversion factor to convert 14.4 cm to m?

1m/100cm

Convert 2280 feet to miles. 1 mi \= 5280 ft.

0.432 miles

Convert 1.555 meters to centimeters

155.5 cm

The result of an unspecified measurement was 1.55863 units. If the accepted value for the quantity is 2.000 units, how would you characterize the result?

not accurate, but precise

T/F: The SI system of measurement is used exclusively in the US

False

(T/F) The unit symbol for a dimension is usually the same as the variable symbol.

False

(T/F) A second is currently defined as 1/86,400 of a mean solar day.

False

T/F; a 60.0 kg object on earth would have the same mass on the moon

True

T/F: The only fundamental SI units are the meter, the second, and the kilogram

False

T/F: The SI unit for luminous intensity is the ampere (A).

False

T/F: Mass is different from weight

True

T/F: All the derived SI units are expressed as combinations of the fundamental SI units.

False