Kinematics and Dynamics

Question 1

Describe how to find the angle of the resultant vector.

Answer 1

Question 2

Explain vectors.

Answer 2

Physical qualities that have both direction and magnitude

Question 3

Scalars

Answer 3

Physical qualities that have magnitude only

Question 4

What is displacement?

Answer 4

Change in position

Question 5

Describe distance.

Answer 5

scalar quantity that reflects the path traveled

Question 6

Describe velocity.

Answer 6

Change in displacement with respect to time

Question 7

Describe force.

Answer 7

-any push or pull that has the potential to result in acceleration
-SI unit= N, or (kg x m)/s^2

Question 8

Gravity

Answer 8

the attractive force between two objects as a result of their masses

Question 9

Explain friction.

Answer 9

a force that opposes motion as a function of electrostatic interactions at the surface between two objects

Question 10

Static friction

Answer 10

-exists between two objects that are not in motion relative to each other
-can take on many values depending on the two materials in contact
-static coefficient is always higher than kinetic coefficient

Question 11

Explain Kinetic friction.

Answer 11

exists between two objects that are in motion relative to each other

wheel rolling down a hill does not experience kinetic friction because the wheel is not sliding across road. The wheel maintains an instantaneous point of static contact with the road, so it experiences static friciton

Question 12

Describe why static friction coefficient will be larger than coefficient for kinetic friction

Answer 12

the coefficient of static friction will always be larger than the coefficient for kinetic friction because it requires more energy to get an object sliding than it takes to keep an object sliding

Question 13

Write the static friction equation.

Answer 13

Question 14

Write the kinetic friction equation.

Answer 14

f(k)= u(k)N
where f(k)=kinetic friction
u(k)=coefficient of kinetic friction
N= magnitude of the normal force

Question 15

Write the force of gravity equation.

Answer 15

F=mg

F=force on object (aka weight of object)
m= mass of object
g=acceleration of gravity (9.8 m/s^s)

Question 16

Acceleration

Answer 16

the vector representation of the change in velocity over time

Question 17

Write the Acceleration equation

Answer 17

Δv/Δt

Question 18

Newton’s first law

Answer 18

aka law of inertia
-an object will remain at rest or move with a constant velocity if there is no net force on the object

F=ma=0

Question 19

Newton’s second law

Answer 19

-any acceleration is the result of the sum of the forces acting on the object and its mass

F=ma

Question 20

Newton’s third law

Answer 20

-any two objects interacting with one another experience equal and opposite forces as a result of their interaction

for every action there is an equal and opposite reaction

Question 21

Kinematics (no final velocity)

Answer 21

x= v(o)t + (at^2)/2

Question 22

Write the Kinematics equation with no displacement)

Answer 22

Question 23

Write the Kinematics equation with no time.

Answer 23

v^2= v(o)^2 + 2ax

Question 24

Kinematics (no acceleration)

Answer 24

x=vt

Question 25

Projectile motion

Answer 25

-contains both an x and y component
-only force action on the object is gravity (assuming negligible air resistance)
horizontal velocity vx is constant

Question 26

Inclined planes equations

Answer 26

force of gravity parallel to plane: F=mgsinѲ
force of gravity perpendicular to plane: F=mgcosѲ

Question 27

Circular motion

Answer 27

-has both radial and tangential dimensions
-if uniform, the only force is the centripetal force, pointing radially inward
-instantaneous velocity vector always points tangentially
in uniform circular motion, the tangential force is 0 because there is no change in the speed of the object

Question 28

Centripetal force

Answer 28

Question 29

Translational equilibrium

Answer 29

-occurs in the absence of any net forces acting on an object
-object has a constant velocity - constant speed and direction
-may or may not also be in rotational equilibrium

Question 30

Rotational equilibrium

Answer 30

-occurs in the absence of any net torques acting on an object
-may consider any pivot point, but center of mass is most common
-angular velocity is usually zero

Question 31

Write the Torque Equation.

Answer 31

r=length of the lever arm
F=magnitude of the force
Ѳ= angel between the lever arm and force vectors

Question 32

dot product

Answer 32

to get a scalar, multiply magnitude of 2 vectors and the cosine of the angle between the 2 vectors
A ⋅ B = | A | | B | cos θ

Question 33

cross product

Answer 33

to get a third vector, multiply magnitudes of 2 vectors and sine of the angle between them
A x B = | A | | B | sin θ

Question 34

Right-hand rule

Answer 34

Question 35

Solving for time it takes an object to fall back to the ground

Answer 35

same as solving for max height because you can solve by setting final velocity to 0 to determine max height and then multiply time by 2

Question 36

any object with a constant velocity has

Answer 36

no net force acting on it

Question 37

sin 90

Answer 37

sin 90 = 1
sin 0 =0

so torque is greatest at a 90 angle and there is no torque when force applied is parallel