Chapter 7: Kinetic Energy & Work

Question 1

What is energy?

Answer 1

It is a quantity that specifies important information about the state of a system–notably, the ability of the system to cause change in physically measurable properties of its environment.
SI unit: joule (J) = kg * m^2/s^2 = n * m

Question 2

Is energy a vector quantity?

Answer 2

No! It is a scalar quantity!

Question 3

Energy comes in three basic forms: ___, ___ and ___.

Answer 3

Kinetic energy; potential energy (gravitational, elastic, electrostatic); rest energy.

Question 4

Energy can be transformed from one form to another, and the total energy of a closed system (can)/(cannot) change.

Answer 4

Cannot

Question 5

What is kinetic energy?

Answer 5

The energy a particle has because of its motion. K = 1/2 * m * (V(subx)^2 + V(suby)^2 + V(subz)^2)

Question 6

What is work?

Answer 6

The transfer of energy between a system and its surroundings by means of a force.

Question 7

Work is done by a ___.

Answer 7

Force

Question 8

Work done by a constant force is:

Answer 8

W(subf) = F(arrow) * Δr

Question 9

Is work a vector quantity?

Answer 9

No! It is a scalar quantity.

Question 10

When work is done by the ___ forces acting on a particle, energy is transferred to or from the particle.

Answer 10

External

Question 11

W(net) = …

Answer 11

ΔK = K(sub2) - K(sub1)

Question 12

If W(subnet) > 0, then ΔK ___ 0.

Answer 12

>

Question 13

If W(subnet) < 0, then ΔK ___ 0.

Answer 13

<

Question 14

If W(subnet) = 0, then ΔK ___ 0.

Answer 14

=

Question 15

TRUE or FALSE: Forces perpendicular to the motion of the object do work.

Answer 15

False! They do no work.

Question 16

Work done by the gravitational force is demonstrated by the formula W(subgrav) = …

Answer 16

-mgΔy

Question 17

Work done by gravity (is affected by)/(is not impacted by) horizontal distance traveled.

Answer 17

Is not impacted by

Question 18

What is Hooke’s Law?

Answer 18

F(subs) = -kΔx

Question 19

The SI unit of the spring constant K is…

Answer 19

N/m

Question 20

A larger value of K means a ___ string.

Answer 20

Stiffer

Question 21

You can use F(subs) = -kΔx as long as the equilibrium position is ___.

Answer 21

The origin

Question 22

When the work done by the spring constant isn’t constant, you (can)/(cannot) use the standard formula for work.

Answer 22

Cannot

Question 23

Use either ___ or an ___ to get the area under the curve on a graph of ___ vs. ___ to get the work for a specific distance.

Answer 23

Summation; integral; force; distance.

Question 24

On a frictionless banked curve, F(subn) supports (more)/(less than) the weight of the object, meaning F(subn) ___ mgcosθ.

Answer 24

More; >

Question 25

When there is no friction on a banked curve, ___, or ___. This is because the normal force on a banked curve has to support the entire weight of the object and provide the centripetal force necessary to keep it in motion.

Answer 25

F(subny) = mg; F(subny) = F(subn)cosθ = mg

Question 26

If there is not friction, there is a(n) (exact speed)/(range of speeds) where an object will not slip and move up or down the incline.

Answer 26

Exact speed

Question 27

On a banked curve WITH friction, the setup for the equation is the same as without it–except, this time, a friction force directed (up)/(down) the incline, with magnitude ___, must be factored into the equation.

Answer 27

Down; μF(subn)

Question 28

What is power?

Answer 28

The work done over a set time interval.
SI unit: Nm/s = J/s = W (watt)

Question 29

Instantaneous power due to applied force is:

Answer 29

P(subF) = F(arrow) * v(arrow)