Class 2 Flashcards
What is the equation for gravity?
Fg = GMm/r^2
The MCAT loves to talk about 1/r^2
Remember that this R is the distance to the CENTER of the earth, not the surface
What is the sin/cos adjustments for gravitational force on a ramp?
Fg = mg cos(theta) for the down component
Fg = mg sin(theta) for the component parallel to the ramp.
If you are turning can your velocity be constant?
No! Changing direction
What keeps you in your seat on a loop roller coaster?
Centripetal force (acceleration)
What is the equation for centripetal acceleration?
ac = v^2/r
What is the equation for centripetal force?
Fc = mv^2/r
What is the relationship between the velocity and acceleration vectors when traveling in a circle?
They are always perpendicular to one another. V is tangent to the path, a will point towards the center
If you are moving in a curved path, can acceleration be zero?
No
What is centripetal force?
The result of the net physical forces (e.g. gravity, tension, friction, etc.)
Can forces that act perpendicularly to velocity change the speed?
No
“Apparent weight” refers to what?
Normal force (what force a scale would exert on an object).
If a cart is traveling in a loop, what must be equal to the centripetal force when the cart is at the BASE?
The difference between the normal force and weight.
Fn - W = Fc
If a cart is traveling in a loop, what must be equal to the centripetal force when the cart is at the TOP?
The sum of the normal force and weight
Fn + W = Fc
How do you calculate the location of the center of mass for non-uniform objects?
X = Xcm = m1x1 + m2x2 +… / m1 + m2 + …
m= each mass x = position
to account for the mass of the teeter totter/plank, include it and locate that mass in the middle (1/2 way point)
Do you need to use any particular unit for the center of mass equation?
No, because they all cancel out/there are no constants that have different units.
