Question

A train rolls to a stop along a horizontal track without the conductor applying the brakes. What answer choice BEST explains why this occurred?
A)
The train ran out of momentum.
Eliminate
B)
The opposing force of friction stopped the train.
C)
The natural state of the train is not to be in motion.
D)
The force of gravity slowed the train until it stopped.

Answer 1

D The force of gravity slowed the train until it stopped?

Answer 2

b the friction causes to stop

Answer 3

Thanks, should I ask another question here or open a new tab?

Answer 4

however u want to do..

Answer 5

The wavelengths of radio waves are much _______________ than the wavelength of microwaves. Therefore, radio waves carry much __________ energy than a microwave.
A)
longer, more
B)
longer, less
C)
shorter, more
Eliminate
D)
shorter, less

Answer 6

B

Answer 7

c shorter and more

Answer 8

Thanks, i still have a few more.

Answer 9

Why does a skydiver accelerate as she falls to the earth before opening her chute?
A)
because she loses mass during her travel
B)
because she gets further from the airplane
C)
because the force of the earth pulls on her
D)
because fewer forces are present to slow her down as she drops

Answer 10

d

Answer 11

Dolphins communicate using compression waves. Some of these sounds are outside the range of human hearing. Upon spotting a hungry shark, dolphin A sends a message to dolphin B. To send this message as quickly as possible, dolphin A would
A)
send the message under water.
B)
send the message above the water.
C)
sound the message as loud as possible.
D)
sound the message as soft as possible.

Answer 12

a

Answer 13

Ultraviolet radiation is dangerous because it has a high enough energy to damage skin cells. UV radiation is called ultraviolet because it has a frequency which is higher than violet radiation (purple light). Therefore, it has a wavelength which is ___________ than violet radiation.
A)
bigger
B)
smaller
C)
the same size
Eliminate
D)
the square root of

Answer 14

a

Answer 15

Sound proof tiles are made of a porous surface (with lots of holes) so that the sound is not transmitted from room to room. This is a good example of _______________ of sound wave energy.
A)
absorption
B)
amplification
C)
diffraction
D)
refraction

Answer 16

a

Answer 17

Use your knowledge of the properties of the different states of matter to determine in which state sound would travel the fastest.
A)
liquid carbon dioxide
B)
gaseous carbon dioxide
C)
dry ice - solid carbon dioxide
D)
none - sound travels at a constant rate

Answer 18

After this one I will open a new question so it doesn't get buggy.

Answer 19

c

Answer 20

I will open a new question. :)