Unit 1: Kinematics
What units do we use for velocity?
meters per second (m/s)
What equation relates the mass "m" of an object and its acceleration "a" to the net force "F" on the object?
F = ma
What equation do we use to calculate the Kinetic Energy of an object?
KE = 1/2 mv2
What units do we use to measure Resistance?
Ohms
What type of light has the HIGHEST frequency?
Gamma rays
A car increases its speed from 5 m/s to 17 m/s in 3 seconds. What is the car's acceleration during this time?
4 m/s2
(17 - 5)/3 = 12/3 = 4
Jimmy pushes East on a cart with 600 Newtons worth of force. If the cart's mass is 150 kg, what is its acceleration?
3.0 m/s2
What is the conservation of momentum?
The total momentum BEFORE a collision is equal to the total momentum AFTER a collision
Which type of circuit is used if you want the VOLTAGE of all the devices to remain constant?
Parallel
Series keeps CURRENT constant
A skateboarder travels 300 meters North, 200 meters South, and then 100 meters North again. What is her displacement?
400 m North
Which of the following has the greatest inertia?
A 0.42 kg arrow traveling at 25 m/s
--- OR ---
A 0.80 kg baseball traveling at 8 m/s
Has the largest MASS (0.80 kg)
A 0.67 kg skateboard has a total momentum of 15 kg m/s. What is its speed?
22.38 m/s
p = mv 15 = (0.67) * v
This is the magnitude of charge of a single electron or proton.
Light is faster.
Light can travel WITHOUT a medium.
Light travels via TRANSVERSE waves.
A basketball rolling across the court travels at a constant 4.2 m/s. If the basketball court is 15 meters wide, how long will it take the basketball to roll across the court?
3.57 seconds
4.2 = 15 / t
(4.2) * t = 15
t = 15 / 4.2
a = 5 m/s2
F = 250 + 250 - 400 = 100 N
F = ma 100 = (20) * a
Determine the energy of a 4.0 kg book at rest on the top of a 7.0 meter high shelf.
PE = 274.68 Joules
PE = (4)(9.81)(7)
A 240 Ohm lightbulb is plugged into a 110 volt outlet. How much current is passing through the lightbulb?
0.4583 Amps
V = IR 110 = I * (240)
If the velocity of a 1200 Hz sound wave is 340 m/s, its wavelength is...
0.2833 m
v = Lf 340 = L * 1200
A cup attached to a piece of string is filled with water and then swung at 18 m/s in a uniform circular path to prevent the water from spilling. If the radius of the path is 15 meters, what is the cup's centripetal acceleration?
21.6 m/s2
v2/r = 18^2 / 15 = 21.6 m/s2
A spring with a spring constant of 2400 N/m is pulled with a force of 180 N. What is the stretch exhibited by the spring?
x = 0.075 m
Fs = kx 180 = 2400 x
How much force is required to stop a 400 kg cart traveling at 5.0 m/s in 3.0 seconds?
666 Newtons
p = mv = (400)(5) = 2000 kg m/s
J = Ft = 2000 = F(3) 2000/3 = 666 N
A 400 m copper wire with a cross-sectional area of 8.0 x 10^-7 m^2 has a resistance of...
R = 8.6 Ohms
R = pL/A R = (1.72 x 10^-8)(400) / (8.0 x 10^-7)
What color light has a frequency of 5.13 x 10^14 Hz?
Yellow
A ball is dropped near the surface of the Earth and falls for 2.75 seconds. What is the magnitude of the velocity of the ball right before it hits the ground?
27 m/s downwards
g = -9.81 m/s2
vi = 0 m/s
t = 2.75 sec
vf = vi + at
vf = 0 + (-9.81)(2.75)
vf = -27 m/s
A 2.0 kg disc experiences a frictional force of 2.94 N as it slides across a surface. What is the coefficient of friction between the disc and the surface? (Bonus: What materials could these be made of?)
u = 0.15 (Rubber on ice)
Ff = uFn 2.94 = u * (9.81)(2)
How much energy is lost due to heat after a 0.33 kg box falls from a height of 4.0 meters if it hits the ground traveling at 8.0 m/s?
2.39 Joules
PE = (.33)(9.81)(4.0) = 12.95 Joules
KE = (.5)(.33)(8^2) = 10.56 Joules
Q = 12.95 - 10.56
A parallel circuit contains two 20 Ohm computers and a 50 Ohm radio. If the circuit is powered by a 100 volt battery, what is the total current running through the circuit?
12 Amps
100 V = I * 20 Ohm I = 5 Amps
100 V = I * 50 Ohm I = 2 Amps
A light wave traveling in a vacuum has a wavelength of 8.62 x 10^-9 m. What is its frequency?
3.48 x 10^16 Hz
v = Lf 3.00 x 10^8 = (8.62 x 10^-9) * f
A train accelerates from rest and travels 300 meters in 20 seconds. What is the trains acceleration during this time?
1.5 m/s2
300 meters / 20 seconds = 15 m/s AVERAGE
0 m/s INITIAL (at rest)
30 m/s FINAL (if average is 15)
30 m/s / 20 seconds = 1.5 m/s2 acceleration
A car with rubber tires traveling on a dry concrete road skids to a stop after moving at 18.0 m/s. If the mass of the car is 2000 kg, how long will it take for the car to slow to a stop?
2000*9.81 = 19620 N
Ff = .68*19620 = 13341 N
F = ma 13341 = 2000*a a = 6.67 m/s2
18/6.67 = 2.70 seconds
How quickly can a 1500 Watt motor lift a 180 kg box a distance of 3.0 meters?
3.53 seconds
P = W / t = Fd / t
1500 = (180)(9.81)(3.0) / t
A 300 Watt generator is connected to a series of three identical light bulbs, with a total current of 3.5 Amps. What is the resistance of each light bulb?
8.167 Ohms
P = VI 300 = V * (3.5) V = 85.7 V
V = IR 85.7 = 3.5 * R R = 24.5 Ohms
What type of light has a photon with an energy of 2.82 x 10^-24 Joules?
Radio Waves or Microwaves (4.3 x 10^9 Hz)
Ep = h * f 2.82 x 10^-24 = (6.63 x 10^-34) * f