1D Motion
What is the graph of acceleration look like when an object has constant velocity?
Flat line at 0
An object traveling in uniform circular motion will be traveling at a constant speed but have acceleration 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.
Is gravity an attractive or repulsion force?
Gravity is an attractive force - it pulls things towards each other
What does net force mean?
It is the sum of all forces acting on an object
An object at rest has how much kinetic energy?
Since kinetic energy is the energy of motion, if an object is at rest, it has 0 N of kinetic energy
A boy walks 150 m in 95 seconds. Calculate the average velocity of the boy.
1.58 m/s
Velocity = displacement/time
The term centripetal means....
Center seeking
Light doesn't exert a force of gravity because it doesn't have this property...
Light doesn't have mass
How much does a 10 kg object weigh on Earth (in newtons)?
98 N
Weight, or the force of gravity, can be calculated using F = ma where a is the acceleration of gravity (9.8 m/s2)
At what point does a rollercoaster have the most potential energy?
a. Before it drops from the highest point
b. As it is falling
c. When it's at its lowest point
a. Before it drops from the highest point
A car accelerates at a constant rate from 8 m/s to 30 m/s in 3.5 second. What is the acceleration of the car?
a. 30.0 m/s2
b. 6.29 m/s2
c. 26.5 m/ss
d. 105 m/ss
b. 6.29
To find the velocity of an object moving in uniform circular motion, I can divide ______ by time. This value represents the displacement around a circle.
Circumference
(the whole way around a circle, the equation is
2*pi*r - you will be given this)
When calculating the force of gravity, distance between two objects is measured from their ______
Distance is measured from the centers of two objects
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?
a = 4 m/s2
3,600 J
ME = KE + PE
A ball is thrown downward off a 50 m cliff with an initial velocity of 15 m/s. How fast is the ball going right before it hits the ground?
a. 34.7 m/s2
b. 13.8 m/s2
c. 55.0 m/s2
d. 41.3 m/s2
a. 34.7 m/s2
What is the centripetal acceleration of an object traveling 4 m/s around a circle that is 12 m across?
2.67 m/s2
v = 4 m/s
r = 6 m
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?
20 N
Since one of the masses doubled, the force of gravity would also double
An asteroid going 200 km/s is struck by two rockets on its north and south face. They both collide into the asteroid with a force of 300 N. How will the asteroid's motion change due to these collisions?
a. The asteroid's velocity will decrease
b. The asteroid will come to a stop
c. The asteroid's velocity will increase
d. The asteroid will maintain the same velocity
d. The asteroid will maintain the same velocity
A ball is dropped from a 10 m height. What happens to the mechanical energy of the ball as it is falling?
a. The mechanical energy decreases
b. The mechanical energy increases
c. The mechanical energy stays the same
d. There is no mechanical energy
c. The mechanical energy stays the same since mechanical energy is conserved.
Even though the object is losing potential energy, it is gaining it as kinetic energy
Position vs time - Upside down parabola
Velocity vs time - Negative slope
Acceleration - Constant negative value (-9.8 m/s2)
A toy car is rounding a circular track with a radius of 1.50 m. The car goes around the track once every 10.0 seconds. What is the centripetal acceleration of the car in m/s2?
(Circumference = 2*pi*r)
0.59 m/s2
Find velocity first and then plug it into the centripetal acceleration equation
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?
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.
An object has four forces acting on it.
7.4 N Up
3.6 N to the Right
3.6 N to the Left
Unknown force Down.
If the object is experiencing a net force of 12.5 N down, what is the magnitude, in Newtons, of the unknown force?
19.9 N Down
What happens to the kinetic energy of a car as it abruptly breaks to a stop on a flat road?
a. It is converted to potential energy
b. It is converted to heat and sound energy
c. It stays the same
d. It disappears
b. 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 break pads against the tires)