Chapter 1: Kinematics

Question 1

Vector definition

Answer 1

Vector has a magnitude and direction. Like displacement, force, and velocity

Question 2

Scalar definition

Answer 2

Scalars are numbers that have magnitude but NO direction. Distance, speed, energy, pressure, mass, are all scalar numbers.

Question 3

Adding vectors

Answer 3

Use tip to tail method, Pythagorean theorem

Question 4

Subtracting vectors

Answer 4

Use tip to tail but make one vector negative A-B=A + (-B) so B has same magnitude BUT OPPOSITE DIRECTION!

Question 5

Multiplying vectors and scalars

Answer 5

When you multiply vector and scalar the magnitude will change AND the direction will be parallel OR anti parallel. N= V |s| where N is the new vector and s is scalar and V is vector. If s is positive then the direction if N is parallel and in same direction. Opposite of negative s.

Question 6

Multiplying two vectors( scalar equation, 3rd vector torque, right hand rule)

Answer 6

When multiplying two vectors like force and displacement, you multiply magnitude and cosine of angle between.

Scalar equation: A B=|A||B| cos angle
3rd Vector Torque: A B=|A||B| sin angle ( right hand rule)
Right hand rule: C=A*B where C is new resultant vector and palm of hand , A is the thumb, B is longer finger

Question 7

Displacement definition

Answer 7

Object in in motion may experience a change and its position which is displacement. Displacement is only The beginning and end of the destination not everything in between. Everything in between is distance.

Question 8

Velocity definition

Answer 8

Velocity is a vector. Magnitude for velocity is the rate of displacement change in meters per second m/s. Direction of velocity vector is the same as the displacement vector. If displacement is zero velocity is also zero

Velocity= change in X/ change in T
Speed : rate of actual distance traveled
Instantaneous speed = instantaneous velocity: V= lim change X / change in T, where X is position and T is time

Question 9

Force definition

Answer 9

Force is a vector quantity experience by pushing and pulling up to objects it’s measured in newtons N which is Kg*m/ s^2.

Question 10

Gravity and gravitational force

Answer 10

Gravity is a force and is equal to 10 m/s^2 on earth.

Gravitational force between two objects: Fg=Gm1m2/ r^2
, big G is universal gravitational constant 6.67x10-11 Nm2/kg2,
r is
The distance between the Two objects centers of mass

If Fg Is quadrupled, r is halved
If m1 is tripled than Fg will triple

Question 11

Friction definition

Answer 11

Friction is a type of force that opposes movement of objects. It always opposes an objects motion causing it to slow down or become stationary. There are two types of friction static friction and kinetic friction.

Question 12

Static friction (Fs)

Answer 12

A stationary object and its surface have static friction.

0<_ Fs <_ us N 

us is the coefficient of static friction. It is a unitless quantity that is dependent on the two materials in contact.

N is the normal force. a component of the force between two objects in contact it is perpendicular to the plane of the contact between the object and the surface that is resting on

Question 13

Kinetic friction (Fk)

Answer 13

Kinetic friction exists between a sliding object and the surface over which the object is sliding. Attire on black ice or an icy patch has kinetic friction whereas a tire and normal road pavement have static friction.

Fk=uk N
Coefficient of kinetic friction will have a constant value for any given combination of a coefficient of kinetic friction and normal force

The coefficient of static friction will always be greater than the coefficient of kinetic friction because it takes more force for an object to start sliding then it is to keep an object to continue sliding

Question 14

Mass and weight

Answer 14

Mass is the measure of inertia in an object. Mass will be the same number anywhere including earth or space because it is not contingent on gravity. The SI unit for mass is kilograms.

Weight however is the measure of gravitational force on an objects mass it is a vector so the SI unit is Newtons.

Weight=Fg= m* g, where m is mass and g is 9.8 on earth

Center of mass/gravity=m1 * x1 + m2*x2 / m1+m2

Question 15

Acceleration (a)

Answer 15

Acceleration is the rate of change in velocity in object experiences due to an applied force. The SI unit for acceleration is meters per second squared.

a=change in velocity/ change in time 

Question 16

Newton’s first law

Answer 16

First law: F net= Ma =0
An object at rest or in motion with constant velocity will remain in motion unless a net force acts upon it. The first law is also known as the law of inertia.



Question 17

Newton second law

Answer 17

F net= Ma
An object of mass M will accelerate when the vector sum of the forces result in a nonzero resultant force factor. No acceleration will occur when the vector sum of the forces results in a cancellation of those forces. The net force and acceleration factors point in the same direction. 

Question 18

Newtons third law

Answer 18

Fab= -Fba
To every action there is an opposite but equal reaction. Physical contact is not necessary for newtons third reaction. 

Question 19

Linear motion

Answer 19

V= V initial + aT, a is acceleration and T time

X= V initial T + at^2/2, for finding position using displacement

V^2= v^2initial + 2ax This is final velocity

X= Vaverage * T

In most cases you will see linear motion shown as a ball dropping in this case acceleration is the same as gravity on earth 9.8 m/s. Object will not reach terminal velocity this is freefall.

When asked to find maximum height it is the same as the object falling back down to starting so you may use final velocity = to zero.

Question 20

Projectile motion

Answer 20

Like a canon, bullet, or baseball, an object experiencing two paths in different directions with two different velocities and accelerations has projectile motion. This is usually in the horizontal and vertical direction as force and gravity or acting upon the object. The Vy is based on gravity and Vx is constant.

When finding time of an object experiencing projectile motion multiply initial velocity by sine angle. Then plug into 0= Vnew * T + aT2/ 2,
a is 9.8 gravity

Define position multiply initial velocity to cosine angle. Then position is new velocity multiplied by final time.

Question 21

Inclined planes

Answer 21

Incline planes are another example of motion in two dimensions. An object on an inclined plane has two force vectors parallel and perpendicular to the plane.

Fg perpendicular= mg * cos0

Fg parallels= mg* sin0

If there’s no acceleration in the perpendicular direction the normal force is equal to perpendicular component of gravity.

The acceleration in the parallel direction will be G multiplied by sine of angle

Question 22

Centripetal acceleration

Answer 22

A part of uniform circular motion an object moving in circular path path has a tendency to break out of that path and move in a linear tangent direction.

However, centripetal force has a force pointed radially inward keeping that object in the circular pathway. And uniform circular motion the tangential force is zero because there’s no change in the speed of the object. Centripetal force generates centripetal acceleration.

Fc = mv^2/r, where v is speed not velocity

The net force vector and the acceleration vector are in the same direction.

Question 23

Transitional equilibrium

Answer 23

Transitional equilibrium is reached when the sum total of all forces acting on an object is zero. The object does not accelerate which means that the object is either stationary or has a constant velocity.

The object experiences transitional equilibrium when there is a constant velocity, constant speed and constant direction.

No acceleration no net force on the object. Because force is equal to mass times acceleration.

If two blocks are ecstatic equilibrium held together by a string or pulley the mass of an object is equal to the mass of the first object multiplied by the static coefficient.



Question 24

Rotational equilibrium with Torque

Answer 24

An object rotating around a fixed point called a fulcrum with a torque force applied. The distance between the force and the full crumb is called the lever arm.

Torque= r * F= rF sine angle where R is lever arm

Clockwise torque is negative
Counterclockwise torque is positive

Question 25

SOH CAH TOA

Answer 25

Sign is opposite over hypotenuse

Cosine is adjacent over hypotenuse

Tangent is opposite over adjacent