2: Newtonian Mechanics Flashcards
(40 cards)
Force
(F) is a vector quantity that is experienced as pushing or pulling on objects
SI unit of Force
Newton (N) = kg*m/s^2
Mass
(m) Measure of a body’s inertia - the amount of matter in something
- Scalar
SI unit of mass
kg
Weight
(W) measure of gravitational force, usually that of earth, on an object’s mass
-Vector
SI unit of weight
Newton (N)
W=
mg
Acceleration (a)
The rate of change of velocity that an object experiences as a result of some applied force
-Vector
SI unit of acceleration
m/s^2
Deceleration
acceleration in the direction opposite the initial velocity
Body in motion, stays in motion
F=ma = 0
2nd law
Sum F = ma
Equal and oppositie
Fb = -Fa
Gravity ______ with height above the earth and __________ the closer you get to the earth’s center of mass.
Decreases
Increases
If there is no acceleration
Then there is no net force on the object
- This means that any object with a constant velocity has no net force acting on it
Net force
Sum of all forces acting on an object
- Even though the force of gravity is always acting on us, the net force on our bodies will be zero, unless there is no ground below us pushing back up against gravity
Gravity
An attractive force that is felt by all forms of matter
- Weakest of the four types of forces
The magnitude of the gravitational force is
Inverse to the square of the distance
- That is, if r is halved, the F will quadruple
F =
Gm1m2/ r^2
- Where G is the universal gravitational constant (6.67x10^-11 Nm^2/kg^2), m1 and m2 are the masses of the two objects and r is the distance between their centers
Translational motion
When forces cause an object to move without any rotation about a fixed point in the object
- Common on the MCAT
Rotational motion
When forces are applied against an object in such a way as to cause the object to rotate around a fixed pivot point, also known as the fulcrum
- Generate torque and moment of force
Torque
Generates the rotational motion, not the mere application of force itself
- This is because torque depends not only on the magnitude of the force but also on the angle at which the force is applied against the lever arm as well as the distance between the fulcrum and the point of force application
- T = rF sin theta
Where F is the magnitude of force, r is the distance between the fulcrum and the point of force application, and theta is the angle between F and the lever arm
Circular motion
When forces cause an object to move in a circular pathway
- Upon completion of one cycle, the displacement of the object is zero
- F = mv^2/r
For circular motion that demonstrates a constant speed at all points along the pathway
The instantaneous velocity vector is always tangent to the circular path