Motion and force Flashcards
How do you determine the velocity and the peak height of a projectile in a linear, uniform motion?
h = (1/2) (v^2/g) v = square root of 2*g*h
How do you determine the average velocity?
Take the average of the initial and final velocity.
Vavg = 1/2 (Vo + Vf)
How does the mass of an object affect air resistance?
What factor affects air resistance?
Mass does not affect air resistance
The main factor affecting air resistance is the number of collisions between the object and air/medium
T/F projectile motion is always symmetrical in absence of air resistance
True
What is the center of mass?
Does it have to be located within the object?
Single point of object which a single force can be applied in any direction to cause all points in the system to accelerate equally. Center of mass is where it is considered to have concentrated mass.
Does not have to be located on the object
What equation determines the net force on an inclined plane?
Mg (sin 0)
What equation determines the normal force on an inclined plane?
Mg cos 0
What does Hooke’s law describe?
Object’s ability to “remember” and retain it’s original shape upon deformation. This force opposes the force causing deformation
F = -k * change in x
Fracture point vs. Yield point
Fracture point is the point where the object breaks
Yield point is the point where the object loses its ability to retain some of its original form.
Torque
Measure of force’s ability to cause rotational acceleration
In torque, where is the net force acted upon
Center of mass
Torque equation
Torque = Fr sin 0
Force and lever arm angle
90
Equilibrium
No net force
Static vs dynamic equilibrium
Zero velocity
Constant velocity
Unit of energy
Joule
N*m
Kg* (m^2/s^2)
How is energy divided
Mechanical vs. non-mechanical
Macroscopic vs. non-macroscopic
Types of potential energies
What does potential energy depend on
Gravitational potential energy
Elastic potential energy
Potential energy depends on where it is located
Universal Gravitational potential energy
Increase in distance corresponds to what
Ug = - G m1m2/r
Increasing distance corresponds to decreasing energy (negative sign)
Gravitational potential energy near the earth surface
Mgh
Elastic potential energy
Ue = (1/2)kx^2
Kinetic energy
(1/2) mv^2
K in hooke’s law
Unit and equation.
Force/ change in x
The extent to which the material resists deformation
N/m
Formula for work
What does work represent
W = Fdcos0
0 = angle between force and d
Energy transferred to a system due to force
Power
Unit
Equations
Amount of work done by a force per unit time
W/t = change in energy/t
Change in energy is work + heat
Watt = J/s
Instantaneous power due to force
P = F*v cos0
Angle between force and velocity
Force is in direction of velocity
Scalar quality does not have direction
Machines and mechanical advantage
Effect on force and work
Reduce force but do not change work
Ramp, lever, pulley
Ramp
Increase the distance which force is applied reducing force needed to get the work done
Work stays the same
Ramp force and work equations
Which side is distance on the triangle
Force = mg (h/d)
Work = Mgh
Distance = hypotenuse
Lever work and force equations
F = mg (L1/L2)
W = Mgh
L1 distance from object to fulcrum
L2 distance from fulcrum to applied force
Pulley
Equation for force and work
Work = Mgh
Force = mg/ number of tensions attached to mg
If the force is halved, the force must be applied over twice the distance
In projectile motion, what determines the time of flight of an object?
It is only the vertical component that determines the time of flight y = 5t^2. Depends on the height and gravitational force acting downward.
What is the difference between mass and weight?
Mass is the object’s tendency to maintain its inertia, to resist change in motion. Weight is m*g in newtons, Gravitational force an object experiences when the object is close to another large body like the earth.
Mass and weight are related but not the same thing.
What is the difference between G in the law of universal gravitation and g?
G can be applied anywhere in the universe whereas the small g only applies on earth.
How is it that the horse is able to pull the cart when there is an equal and opposite force?
The forces act on different “systems”
T/F static friction tends to be greater than kinetic friction
TRUE
How does the acceleration of an object compare when the object budges versus while the object is moving?
The acceleration of the object while it’s moving is greater
How does the net force applied to an object compare when the object budges versus while the object is moving?
The net force applied while the object is moving is greater.
Normal force of the inclined plane
Mg*cos(0)
