Lecture 2

Question 1

What are the components of force?

Answer 1

• point of application
• line of application
• direction of push or pull
• magnitude

Question 2

What is a vector?

Answer 2

magnitude and direction

Question 3

what is a scalar?

Answer 3

magnitude

Question 4

what is internal forces

Answer 4

• act within the object or system
• joint reaction force and keep joint together
• muscles as a means for motion

Question 5

what is an external force

Answer 5

• act on an object as a result of its interaction with the environment
• can change the motion of the body center of mass
• contact vs. non contact

Question 6

What are non contact forces

Answer 6

these are forces that occur even if objects are not touching each other
–gravity (g)

Question 7

What is gravity

Answer 7

gravity is a non contact force and the force of gravity acting on the body is weigth
[W=mg or F=ma]
** acceleration due to gravity is =9.81 m/s2

Question 8

What are contact forces

Answer 8

forces that occur between objects in contact with each other

• they can either be soild or liquid
• and can be resolved into componenet forces
• *parallel (friction)
• *perpendicular (normal)

Question 9

What is the resultant force

Answer 9

this is the sum of the X and Y forces acting on a object

Question 10

what is friction ?

Answer 10

a force acting over the area of contact between tow surfaces

• the direction is opposite of motion or motions tendency
• determines the relative ease of difficulty of motion for tow objects in contact
• magnitude is the product of the coeffiecient of friction and the normal reaction forces

Question 11

what is static friction

Answer 11

friction force between two non moving surfaces

(friction is applied equally in an upward line

Question 12

what is kinetic friction

Answer 12

friction force between two moving surfaces

the friction is constant in a stright line

Question 13

what is max static friction

Answer 13

this is the highest point before movement

Question 14

What are colinear forces

Answer 14

these are forces that act in the same or opposite direction and are very simple to calculate

Question 15

what are the 4 directions and their value

Answer 15

Left= negative
Right= positive 
Down = negative
Up= positive

Question 16

how do you connect vectors

Answer 16

tip to tail
1 place a V at the origin
2 place the tail of the other V at the tip of the 1st
3 then the resultant V is the straight line from the tail of the 1st V to the Tip of the last V

Question 17

what is the net force

Answer 17

is the sum of all external forces

Question 18

what is sin

Answer 18

o/h

Question 19

what is cos

Answer 19

a/h

Question 20

what is tan

Answer 20

o/a

Question 21

when is soh cah toa used

Answer 21

when looking at a 90 degree angle

Question 22

when do you use law of cosines

Answer 22

when you dont have a 90 degree angle

A2 + B2 -2ABcos=C2

Question 23

What are torques

Answer 23

the rotary effect of a force about an axis of rotation
T=Fd
-turning effect produced by a force
-angular equivalent of a force
- also called moments of force or moments

Question 24

where do you find the moment arm

Answer 24

the moment arm is the perpendicular from the force line of action to the axis of rotation

Question 25

Look at the lecture many equations and examples

Answer 25

would be good to look at

Question 26

Equation of force

Answer 26

F=ma (N)

Question 27

Equation of pressure

Answer 27

P=F/A (N/m)

Question 28

Equation of Inertia (sum of all particles )

Answer 28

I=sum mr^2

Question 29

Equation of work

Answer 29

W=Fd (Nm) or (J)

Question 30

Equation of efficiency

Answer 30

%efficiency= Work output/ work input x 100

Question 31

Equation of potential energy

Answer 31

PE=mgh

PE=1/2kd

Question 32

Equation of kinetic energy

Answer 32

KE=1/2mv^2

Question 33

Equation of total energy

Answer 33

TE= PE+KE
TE= mgh + 1/2mv^2

Question 34

Equation of power

Answer 34

linear → P=Work/time
rotatory → P= Work/time
(watts or J/sec)