Work & Energy
A 50 kg boy and a 25 kg girl run up a 10 m flight of stairs. The boy reaches the top in 5 seconds and the girl reaches the top in 2.5 seconds. How much work does the girl do compared to the boy? How much power does the girl exert compared to the boy?
Work of the girl is 1/2 of the boy. Power of the girl and boy is the same.
Which of the following objects: a 5 kg object travelling at 30 m/s or a 100 kg object traveling at 5 m/s; has the greatest momentum?
Two negative charges attract or repel?
Repel
What are the four factors that affect the resistance of a wire?
thickness, material, temperature, and length
What is the frequency of a wave with a period of 5 seconds?
f = 0.20 Hz
A student mixes 150 mL of water at 20 degrees C with 150 mL of water at 90 degrees C. What is the final temperature of the water?
Tf = 55 degrees C
What is the acceleration of a 1500 kg car as it comes to rest with a force of 900 N in 3 seconds?
a = -0.6 m/s2 (backward)
If a conductor is in electrostatic equilibrium, the electrical field inside the conductor is?
Zero.
A blender has a resistance of 44 ohms on a 120 V circuit. Calculate the power usage of the blender.
P = 327 W
Does the amplitude affect the speed of the wave?
No, only frequency and wavelenth
An average force of 52 N is used to pull back the string of a bow and arrow by 0.55 meters. What is the kinetic energy of the arrow as it leaves the bow?
KE = 28.6 J
Two lab carts are initially at rest with a compressed spring between them. Cart A is half the mass of cart B. When the spring is released, what is the velocity of cart A compared to cart B?
Cart A has twice the velocity of cart B.
What do you call the process of charging a conductor by bringing it near another charged object and then grounding the conductor?
Induction
How is current effected when the number of charge carriers increases?
Current increases.
What type of wave is a sound wave?
Longitudinal, compressional wave.
A 56 kg skateboarder on a skateboard is at the top of a ramp with a vertical height of 6 m. What is the skate-boarder's maximum kinetic energy at the bottom of the ramp?
KE = 3293 J
A 800 kg railway car is moving at 4 m/s to the left. It collides with an attaches to a 300 kg railway car that is initially at rest. What is the final velocity of the two cars?
Vf = -2.9 m/s (to the left)
What does it mean when the electric field lines of force are closer together?
The electric field is stronger.
What type of field force is caused by the flow of electricity or current?
Magnetic field
Explain the Doppler Effect in terms of wave amplitude and frequency when a sound produced by a moving object is heard by a stationary observer.
A frequency shift results from the relative motion between the source of the sound and the observer. The frequency appears to be higher than the actual frequency to the observer as the source moves closer and lower as the source moves away. The amplitude increases as the source gets closer.
List the states of matter with the lowest to highest entropy?
solids, liquids, & gases
At a WWII re-enactment, a 40.0 kg cannonball is fired horizontally to the right at 20 m/s from a cannon with a mass 500 kg. What is the recoil speed of the cannon?
Vcannonf = - 1.6 m/s (left)
Two point charges originally 5 cm apart are moved to a distance of 20 cm apart. By what factor does the resulting electric force between them change?
By a factor of 1/16.
A fridge at your house uses 5.2 A of electricity when it operates on a 120 V circuit. If the electricity costs $0.12 per kW*hr, what would it cost to run the fridge for one day? Assume that the fridge is on for 24 hours at the same temperature.
Cost = $ 1.80
Put the following waves in order from shortest to longest wavelength: radio, x-ray, visible, microwave, gamma, ultra-violet, and infra-red.
GR, XR, UV, VL, IR, MW, R