Dynamics; School of PE

Question 1

Dynamics

Define Dynamics

Answer 1

Dynamics is the study of Moving Objects

Question 2

Dynamics

Define Kinematics

Answer 2

• The study of a body’s motion independent of the forces on the body
• Doesn’t ask about Forces; Only motion

Question 3

Dynamics

Define Kinetics

Answer 3

• The study of motion and the forces that cause motion.
• Combines Dynamics and Kinematics

Question 4

Dynamics; Kinematics

Expaln the relationship between position, velocity, and accelleration

Answer 4

s= position

v= velocity= change in postion with respect to time (Derivative of postion)

a=acceleration= change in velocity with respect to time (Derivative of Velocity)

Question 5

Dynamics; Kinematics; Circular Motion

Explain the relationship b/w posistion velocity, and acceleration b/w statics and Dynamics

Answer 5

Postiion = s=

Question 6

Dynamics; Kinematics; Circular Motion

Angular Velocity=

Answer 6

Question 7

Dynamics; Kinematics; Circular Motion

Angular Acceleration=

Answer 7

Angular Acceleration is equal to tangential velocity divided by the radius

Question 8

Dynamics; Kinematics; Circular Motion

Tangential Acceleration=

Answer 8

Tangential Acceleration= a_t

= radius time the angular acceleration

Question 9

Dynamics; Kinematics; Circular Motion

Normal Acceleration =

Answer 9

Normal Acceleration= a_n = radius times angular velocity squared = tangential velocity squared divided by the radius

Question 10

Dynamics

Momentum=

Answer 10

Momentum= Mass times Velocity

Question 11

Dynamics; Kinetics; Impulse & Momentum

• Impulse=
• Impulse Momentum Principle=

Answer 11

• Impule= For X Change in Time

Imp= F * t

• Impulse Momentum Principle; Refer to Picture

Impuls is a change in momentum

Imp = Δ p ► F * t = m * ΔV

Imp= F * t = m * a * Δ t = m * (ΔV / Δt ) * Δ t = m * Δ V

=

Δ p = m *ΔV

Question 12

Dynamics; Energy

Any form of energy can be converted into-

Answer 12

any other form of energy

Question 13

Dynamics; Energy

Explain Equation for Work

Answer 13

Question 14

Dynamics; Energy

Equations for Kinetic Energy of a Mass

Answer 14

Question 15

Dynamics; Energy

Kinetic Energy of a Rotation Body

Answer 15

I is called the mass moment of inertia; It indicates how hard it is to rotates something (Totaly different then the First Moment of Inertia

Question 16

Dynamics; Energy

Potential Energy Equations

Answer 16

Potential Energy is related to something height, or change in height

Question 17

Dynamics; Energy

Potential Energy for a Spring and work done by a spring

Answer 17

Question 18

Dynamics; Constant Acceleration

Provded equations for Constant acceleration

Answer 18

position; s = 1/2(at²) + V_ot + X₀

velocity; V=at + V₀

acceleration= dV/dt = change in velocity with respect to time

Question 19

Dynamics

What is the difference between the mass moment of Inertia, and the first Moment of Inertia

Answer 19

The mass moment of Inertia indicates how difficult it is to rotate something;

The First moment of Inertia is concerned with the cross sectional area of a part; does not involve mass, only dimensions

Question 20

Dynamics; Energy

Explain Conservation of Energy for a closed system.

Answer 20

If nobody else is pushing or pulling on the system then you can convert potential energy into kinetice energy and back anf forth as much as you want.

Question 21

Dynamics; Energy

Explain Conservation of Energy for a system with external work-

Answer 21

When somebody starts applying a force to a system (Force times Distance= work), it will change the energy of the system.

Question 22

Dynamics; Energy

What does e stad for?

Answer 22

e= coefficient of restitution; it tells us how much of the kinetic energy stayed with the object, and not transferred soemwhere else.

Example; Basketball flat versus full; When dropped it bouces a little less higher every time. Thats because the energy went to heating up skin of basketball, heated up air in the basketball, heated up the floor, made alot of sound.

Question 23

Dynamics

What does e (coefficient of resitiution) reprent in the example of dropping a basketball.

Provide definition / equation

Answer 23

How much velocity it had when it hit the floor is restored to it when leaving the floor

By definition, it is the departure velocity of the 2 objects relative to each other divided by the approach velocities

Question 24

Dynamics; Energy

What is a inelastic collision

What is e in a elastic Collision

What is e in a inelastic collision

Answer 24

Inelastic Collision is when the coefficient of restitution (e) departure = 0.

For example, if you drop a flat basketball, it wont bounce. This is a completly inelatic collision with the ground.

Elastic; e = 1

Inelastic; e = 0

Question 25

Dynamics; Energy

Most Exam questions will be centered around a single concept; either completly elastic, or inelastic. For these type of problems, what equation should be used?

These equations are good for all impact questions.

Answer 25

Both equations are the same below.

Question 26

Dynamics; Kinetics

The Frictional force equation is the same for statics and dynamics. What is it?

What is the difference b/w statics and dynamics

Answer 26

In statics all the forces balance such that nothing accelerated.

In Dynamics all the forces add up to something other then zero, and there is some force left over causing acceleration. Question in dynamics is what force is left ove causing an acceleration.

N= Normal Force (Engineering Term for Perpindicular)

Question 27

Dynamics; Kinetics

Dynamics and Statics bothe use the equation Force = mass X acceleration.

What is the difference in how this equation is used in dynamics compared to statics?

Answer 27

In statics, the acceleration is zero, sum of the forces always equals zero.

In dynamics you have acceleration, so this is not the case.

Question 28

Dynamics; Centripetal Force

Define Centripital Force

Answer 28

The force required to keep a body rotating about an axis.

= m*a_n

= mV²_t / r

= mrω²

Question 29

Dynamics; Rotation

Banking Curve Equation

Epalain how this is similar to Statics

Answer 29

Where does this equation come from– We know that to prevent soemthing from sliding down a curve that tan θ = μ for it to be static. In this case the resistance to motion is not beign provided by friction (μ); It is beign provided by centripital force (V_t² / gr)

Question 30

Dynamics; Vibration

Natural Frequency equation for vibration?

Answer 30

Question 31

Dynamics

What holds true for impacts?

Answer 31

Momentum is always conserved

Question 32

Dynamics

What holds true for Elastic Impacts?

Answer 32

Kinetic Energy is conserved

m₁*v₁ + m₂*v₂ = m₁*v’₁ + m₂v’₂

This is just theory; Can use equation for all impacts to solve these problems.

Question 33

Dynamics

What holds true for Inelastic Impacts

Answer 33

Kinetic Energy does not have to be conserved if some energy is converted to another form

Add Picture from slide 8-8e for All Impacts

Question 34

Dynamics

Explain all of the different equations used for kinematics Circular Postion

Answer 34

Question 35

Dynamics

When you swing a mass around in a circle on the Rope, the outward acceleration is called ____ ____. This creates ____ in the rope, otherwise called a ______ _____. Provide Equation.

Answer 35

Normal Acceleration

Tension

Centripetal Force

F_c = m•a_n = m•r•ω² = m•v_t² / r

Question 36

Dynamics

Provide equation for Angular Momentum

Answer 36

H_o = r•m•v_t = r•m•ω•r = r²•m•ω