Mechanics Review Concepts

Question 1

Position

Answer 1

X - (scalar) the location of an object relative to a chosen origin.

Question 2

Displacement

Answer 2

Change in X - (vector) from initial position to its current position. Change in X = Current position - Initial Position

Question 3

Distance

Answer 3

S - magnitude of displacement or total path length

Question 4

Velocity

Answer 4

V - (vector) ratio of displacement to time. If the change in t is very small, V is considered to be instantaneous. If the change in t is not small, V is an average velocity.

Question 5

Speed

Answer 5

(scalar) magnitude of velocity. average V = change in v/ time

Question 6

Acceleration

Answer 6

a - (vector) the ratio of the change of an object’s velocity, change in v, to time.

Question 7

System

Answer 7

Collection of objects in a process

Question 8

Enviroment

Answer 8

Objects outside of the system

Question 9

Force

Answer 9

F - (vector) push or pull between 2 objects that characterizes their interaction.

Question 10

Force Diagrams (Free Body Diagrams)

Answer 10

Represent all forces on an object or system. Use trig to split x vs y. x or y axis should be in the plane of motion.

Question 11

Newton’s 1st Law

Answer 11

An object with velocity maintains it without change.

Question 12

Newton’s 2nd Law

Answer 12

(F/m)=a. (F/m)=(change in v)/t. F * t =M*(change in v). Impulse = change in momentum

Question 13

Newton’s 3rd Law

Answer 13

2 objects exert equal magnitude and opposite direction forces of the same type on each other.

Question 14

Gravitational Force

Answer 14

(vector) all objects have gravitational fields. 2 objects must be present.

Question 15

Static Friction

Answer 15

F(s) - (vector) force of friction on an object not sliding on the surface. F(s)=Mu(s)*F(n)

Question 16

Kinetic Friction

Answer 16

F(k) - (vector) Mu(k) depends on both surfaces, involves sliding, doesn’t change. F(k)=Mu(k)*F(n)

Question 17

Projectile Motion

Answer 17

Net force is Fg due to earth. Horizontal motion: change in x= V(x)*t. All kinematic equations: a=g.

Question 18

Uniform Circular Motion

Answer 18

Perfect circle. (sum)F is pointed center. a is pointed center. change in V is pointed center. V is tangential to the circle.

Question 19

Collision in an isolated system

Answer 19

(sum)F=0. Kinetic energy isn’t guaranteed to be conserved. Mass conserved.

Question 20

Linear Momentum

Answer 20

P - (vector) the product of mass*velocity. Describes an object’s state. Total momentum of a system is the sum of all momentum of all objects in the system.

Question 21

Impulse

Answer 21

J - (vector) product of the average force exerted on the object during the time interval change in t. J=Ft

Question 22

Generalized Momentum Impulse Theorem

Answer 22

The change in momentum in the system = external impulse. When J=0, the momentum of the system stays constant.

Question 23

Work

Answer 23

W - (scalar) a way to change the energy of a system. Done by external forces W = Fdcos(theta). Depends on the Force, direction of motion, and the angle between them.

Question 24

Gravitational Potential Energy

Answer 24

Ug - (scalar) energy of a system due to the relative separation of 2 objects. Change in Ug=mg*change in y.

Question 25

Kinetic Energy

Answer 25

KE - (scalar) energy of motion depends on m and v. KE=(1/2)mv^2

Question 26

Elastic Potential Energy

Answer 26

Us =(1/2)Kx^2, energy stored in a compressed or stretched spring.

Question 27

Total Mechanical Energy

Answer 27

TME= Ug + Us + K(T) + K(R)

Question 28

Work-Energy Theorem

Answer 28

Work= change in TME = change in k. No work: change in Ug +Us + K(T) + K(R) =change in Ug’ +Us’ + K(T)’ + K(R)’. Work= change in Ug +Us + K(T) + K(R) + W = change in Ug’ +Us’ + K(T)’ + K(R)’.

Question 29

Elastic Collisions

Answer 29

P and change in KE are constant

Question 30

Inelastic Collisions

Answer 30

P is constant, and KE decreases.

Question 31

Totally Inelastic Collisions

Answer 31

Stick Together

Question 32

Power

Answer 32

(change in E)/t = W/t. 1 Watt = 1 J/s

Question 33

Center of Mass

Answer 33

The point at which we can consider all of the gravitational force to be exerted. An external force facing directly towards or away from the center of mass won’t cause rotation.

Question 34

Torque

Answer 34

T - (vector) physical quantity characterizing the turning ability of a force with respect to a particular axis of rotation.

Question 35

Rotational Intertia

Answer 35

Physical quantity I=kmr^2. Depends on mass distribution. Describes an object’s rotation.

Question 36

Rotational Momentum

Answer 36

Conserved just like P. L=I(omega). change in L = torque * t