Exam 2 Flashcards
(38 cards)
In Circular Uniform Motion is velocity constant?
Velocity vector IS.
But velocity direction is NOT.
Circular Acceleration always points to
Center of the circle
When circular acceleration decreases, the radius ____.
Increases
Car moves in straight line, then goes around curve, then moves in another straight line. When is it in equilibrium?
Straight line= equilibrium, speed/direction are constant
Curve= direction changes, circular acceleration.
Uniform Circular Motion
motion of object traveling at constant speed on a circular path
Circular Force points
towards center of circle
Tension and circular force
oppose each other at the point of contact
As speed increases, what happens to tension and circular force.
they increase
Speed increases or a tight turn happens, what happens to angle and circular force?
Increase
Fc=
Fnet required to keep an object moving on circular path
Increasing speed and a decreasing radius leaders to a (flatter/steeper) curve and (smaller/larger) angle
steeper
Larger
How do we know if there is circular motion?
Velocity that changes direction at every moment
Non-zero centripetal acceleration
Non-zero net force (Fc)
Satellites that are CLOSER of Earth,
The Radius (increase/decrease) Orbital Speed (increase/decrease)
Radius Decreases
Orbital speed increases
In what circumstance does force do positive work on an object?
A) The direction of the force is perpendicular to the object’s displacement
B) The direction of the force is in the opposite direction to the object’s displacement.
C) No matter the direction of the force, positive work will be done if there is a displacement of the object.
D) The direction of the force is in the same direction as the object’s displacement.
E) The object’s displacement is zero meters as the force is applied.
D) Direction of Force is same direction as object’s displacement
In which one of the following situations is zero net work done?
a) a bunch of bananas are placed on
a spring scale in the supermarket
b) a sky diver falls from an airplane before opening her parachute
c) a horse pulls a wagon at a constant velocity
d) a snowball rolls down a hill
e) a skateboarder steps on a skateboard and begins to roll
C) Horse pulls a wagon at a constant velocity
Which one of the following is an example of an object with a non-zero
kinetic energy?
a) A train is parked in a train station.
b) A car rests at the top of a hill.
c) The pendulum of a grandfather clock is still.
d) A boulder rests at the bottom of a cliff.
e) The International Space Station orbits the Earth.
E) International Space Station orbits the Earth
Work done by gravity
=mg(height initial - height final)
What makes a force conservative.
Version 1: Work done on moving object is independent of the path between an object’s initial and final positions
Version 2: Does not work on object moving around closed path, starting and finishing at the same point
Conservative Forces
GEE:
Gravitational
Elastic
Electric
Non Conservative Forces
PANTS: Propulsion Force of a Rocket Air Resistance Normal Force Tension Static and Kinetic Frictional Forces
When both conservative and nonconservative forces
W = Wc + Wnc
W= change in KE Wc = Wg = Negative change in PE
Which force equals delta KE and delta PE
Wnc
Total mechanical energy remains constant provided
work done by non-conservative forces is zero
If total energy conserved
Final KE + Final PE = Initial KE + Initial PE
