1D Motion Equations & Graphs
Uniform Circular Motion
Universal Law of Gravitation
Forces
Energy
100
A 10 kg box accelerates on a frictionless surface from 6 m/s to 18 m/s in 3 seconds. What is the acceleration of the box?
a = vf - vi / t
a = (18 - 6) / 3 =
4 m/s2
100
An object traveling in uniform circular motion will be traveling at a constant speed but will be accelerating because ______ is changing
Direction is changing.
Think of being in a car while going through a roundabout. Even though you might be going at a constant 25 mph, the direction you're facing is changing.
100
Is gravity an attractive or repulsion force?
Gravity is an attractive force - it pulls things towards each other
100
Draw all the forces acting on a car that is moving.
100
How much mechanical energy does a toy plane have if it has 600 J of kinetic energy and 3,000 J of potential energy?
3,600 J
ME = KE + PE
200
Draw the position vs time, velocity vs time, and acceleration vs time graphs for an object that has constant positive acceleration.
- Curved position graph going up
- Velocity graph going up
- Flat acceleration graph in the positive
200
A truck is driving at constant speed on the track shown below.
100 pts: Which vector represents the net force acting on the truck?
100 pts: What is this called?
C.
Centripetal
200
Light doesn't exert a force of gravity because it doesn't have this property...
Light doesn't have mass
200
A force of 36.0 N was used to push an object weighing 9.0 kg along a flat, frictionless, horizontal surface. What is the magnitude of the acceleration achieved by the object?
F = ma so a = F/m
a = 36 / 9
= 4 m/s2
200
At what point does a roller coaster have the most potential energy? At what point does the roller coaster have the most kinetic energy?
Most PE - At the top
Most KE - At the bottom
300
A 1200 kg car accelerates from rest to 24 m/s on a 40 m track. What is the acceleration of the car?
a = vf2 - vi2 / 2(d)
a = (242 - 02) / (2x40)
= 7.2 m/s2
300
150 pts: After reaching point 2, which path would the ball follow?
150 pts: What is this called?
C.
It would continue tangential to its circular motion.
300
When calculating the force of gravity, distance between two objects is measured from their ______.
Distance is measured from the centers of two objects
300
If the box has a net force of 4.6 N up, what is the unknown force?
A. 2.2 N B. 6.8 N
C. 11.4 N D. 8.2 N
C. 11.4 N
300
A ball is tossed 10 meters into the air. Describe what happens to the ball's energy as it goes up.
Include KE, PE, & ME in your answer
As the ball goes up, KE is converted to PE but the overall ME stays the same.
400
A rock is dropped from a cliff of an unknown height. If the rock takes 8.7 seconds to reach the ground, how tall is the cliff?
d = (0)(8.7) + 1/2(9.8)(8.7)2
d = 370 m
400
What is the centripetal acceleration of a car traveling 14 m/s around a curve that has a radius of 5 m?
ac = v2 / r
ac = 142 / 5
= 39.2 m/s2
400
Two objects exert a force of 10 N on each other. If one of the masses doubles, what force would they exert on each other?
200 pts: Describe the relationship between Fg and mass
200 pts: What would the new force be?
20 N
Since the force of gravity is directly proportional to the mass of the objects, when one mass doubles, the force also doubles.
400
A 40 kg dolphin experiences 640 N of buoyant force while floating through the water. What is the net force acting on the dolphin? (also provide the direction)
The dolphin has 640 N up
Force down = Fg = m x 9.8 = 392 N down
640 N - 392 N = 248 N up
400
What happens to the kinetic energy of a car as it abruptly breaks to a stop on a flat road?
It is converted to heat and sound energy
As a car breaks to a stop, the friction on the tires will cause them to heat up (burning rubber) and cause a screeching sound (either from the tires against the road or the brake pads against the tires)
500
Draw the position vs time, velocity vs time, and acceleration vs time graph of a ball that is tossed into the air
Position vs time - Upside down parabola
Velocity vs time - Negative slope
Acceleration - Constant negative value (-9.8 m/s2)
500
What is the centripetal acceleration of a car traveling 18 m/s around a roundabout that is 24 m across?
ac = v2 / r
ac = 182 / 12
ac = 27 m/s2
500
Two objects exert a force of 20 N on each other. If the distance between those two objects were to double, what force would they exert on each other?
200 pts: Describe the relationship between Fg and distance
200 pts: What would the new force be?
5 N.
Since the force of gravity is inversely proportional to the square of the distance, when distance is doubled, force is decreased to 1/4th its original amount.
500
A 50 kg cart is traveling at a constant velocity of 15 m/s. If the cart is experiencing 10 N of forward thrust, how much frictional force is acting on the cart?
10 N.
Constant velocity means forces are balanced so if there is 10 N of force forward, there is also 10 N of force backward.
500
Which object has the most mechanical energy?
ME = KE + PE
= 1/2mv2 + mgh
Object A - 87.4 J