Answer:
Concrete
Explanation:
The speed at which sound propagates is medium dependent. As one of the forms of mechanical waves, sound requires a material medium for propagation from place to place.
- Sound travels with the least speed in air because air particles are far apart and they are randomized.
- Sound travels with the greatest speed in solids. Concrete is the only solid material given in the choice.
The speed of sound increases from air to liquid and to solid.
False because opposites attract. :)
Answer:
Newton's Cradle experiment perfectly demonstrates the law of conservation of momentum which states that in a closed system, momentum before the collision is equal to momentum after the collision of the system.
As the first ball swings in the air, it gains momentum. When it strikes the second ball, it loses momentum and second ball gains equal amount of momentum. The second ball transfers the momentum to third, then fourth and till the last. The last ball when gains the same momentum swings up in the air. This continues. This experiment is done in drag free condition. This means there is no loss of momentum or opposing forces present.
<u>Answer:</u>
2.39 kg
<u>Explanation:</u>
There is conservation of momentum here in this problem so we will use the following problem:
where the mass of the student 
is 48.5 kg,
the mass of the skateboard 
is kg,
the initial speed of the student 
is 4.25 m/s; and
the speed of the student and skateboard 
is 4.05 m/s.
So substituting the given values in the above formula to get:
Therefore, the mass of the skateboard is 2.39 kg.
Answer:
Part a)
Part b)
Explanation:
Part a)
In order to have same range for same initial speed we can say
so after comparing above we will have
so we have
Part b)
Time of flight for the first ball is given as
Now for other angle of projection time is given as
So here the time lag between two is given as
