Motion and force

Question 1

How do you determine the velocity and the peak height of a projectile in a linear, uniform motion?

Answer 1

h = (1/2) (v^2/g) 
v = square root of 2*g*h

Question 2

How do you determine the average velocity?

Answer 2

Take the average of the initial and final velocity.

Vavg = 1/2 (Vo + Vf)

Question 3

How does the mass of an object affect air resistance?

What factor affects air resistance?

Answer 3

Mass does not affect air resistance

The main factor affecting air resistance is the number of collisions between the object and air/medium

Question 4

T/F projectile motion is always symmetrical in absence of air resistance

Answer 4

True

Question 5

What is the center of mass?

Does it have to be located within the object?

Answer 5

Single point of object which a single force can be applied in any direction to cause all points in the system to accelerate equally. Center of mass is where it is considered to have concentrated mass.

Does not have to be located on the object

Question 6

What equation determines the net force on an inclined plane?

Answer 6

Mg (sin 0)

Question 7

What equation determines the normal force on an inclined plane?

Answer 7

Mg cos 0

Question 8

What does Hooke’s law describe?

Answer 8

Object’s ability to “remember” and retain it’s original shape upon deformation. This force opposes the force causing deformation

F = -k * change in x

Question 9

Fracture point vs. Yield point

Answer 9

Fracture point is the point where the object breaks

Yield point is the point where the object loses its ability to retain some of its original form.

Question 10

Torque

Answer 10

Measure of force’s ability to cause rotational acceleration

Question 11

In torque, where is the net force acted upon

Answer 11

Center of mass

Question 12

Torque equation

Answer 12

Torque = Fr sin 0

Question 13

Force and lever arm angle

Answer 13

90

Question 14

Equilibrium

Answer 14

No net force

Question 15

Static vs dynamic equilibrium

Answer 15

Zero velocity

Constant velocity

Question 16

Unit of energy

Answer 16

Joule

N*m

Kg* (m^2/s^2)

Question 17

How is energy divided

Answer 17

Mechanical vs. non-mechanical

Macroscopic vs. non-macroscopic

Question 18

Types of potential energies

What does potential energy depend on

Answer 18

Gravitational potential energy

Elastic potential energy

Potential energy depends on where it is located

Question 19

Universal Gravitational potential energy

Increase in distance corresponds to what

Answer 19

Ug = - G m1m2/r

Increasing distance corresponds to decreasing energy (negative sign)

Question 20

Gravitational potential energy near the earth surface

Answer 20

Mgh

Question 21

Elastic potential energy

Answer 21

Ue = (1/2)kx^2

Question 22

Kinetic energy

Answer 22

(1/2) mv^2

Question 23

K in hooke’s law

Unit and equation.

Answer 23

Force/ change in x

The extent to which the material resists deformation

N/m

Question 24

Formula for work

What does work represent

Answer 24

W = Fdcos0

0 = angle between force and d

Energy transferred to a system due to force

Question 25

Power

Unit

Equations

Answer 25

Amount of work done by a force per unit time

W/t = change in energy/t

Change in energy is work + heat

Watt = J/s

Question 26

Instantaneous power due to force

Answer 26

P = F*v cos0

Angle between force and velocity
Force is in direction of velocity

Scalar quality does not have direction

Question 27

Machines and mechanical advantage

Effect on force and work

Answer 27

Reduce force but do not change work

Ramp, lever, pulley

Question 28

Ramp

Answer 28

Increase the distance which force is applied reducing force needed to get the work done

Work stays the same

Question 29

Ramp force and work equations

Which side is distance on the triangle

Answer 29

Force = mg (h/d)

Work = Mgh

Distance = hypotenuse

Question 30

Lever work and force equations

Answer 30

F = mg (L1/L2)

W = Mgh

L1 distance from object to fulcrum

L2 distance from fulcrum to applied force

Question 31

Pulley

Equation for force and work

Answer 31

Work = Mgh

Force = mg/ number of tensions attached to mg

If the force is halved, the force must be applied over twice the distance

Question 32

In projectile motion, what determines the time of flight of an object?

Answer 32

It is only the vertical component that determines the time of flight y = 5t^2. Depends on the height and gravitational force acting downward.

Question 33

What is the difference between mass and weight?

Answer 33

Mass is the object’s tendency to maintain its inertia, to resist change in motion. Weight is m*g in newtons, Gravitational force an object experiences when the object is close to another large body like the earth.

Mass and weight are related but not the same thing.

Question 34

What is the difference between G in the law of universal gravitation and g?

Answer 34

G can be applied anywhere in the universe whereas the small g only applies on earth.

Question 35

How is it that the horse is able to pull the cart when there is an equal and opposite force?

Answer 35

The forces act on different “systems”

Question 36

T/F static friction tends to be greater than kinetic friction

Answer 36

TRUE

Question 37

How does the acceleration of an object compare when the object budges versus while the object is moving?

Answer 37

The acceleration of the object while it’s moving is greater

Question 38

How does the net force applied to an object compare when the object budges versus while the object is moving?

Answer 38

The net force applied while the object is moving is greater.

Question 39

Normal force of the inclined plane

Answer 39

Mg*cos(0)