Answer:
Density is determined by an object's mass and volume.
Explanation:
If two objects take up the same volume, but one has more mass, then it also has a higher density.
Answer:

Explanation:
The energy difference between the energy levels involved in the transition of the electron is directly proportional to the frequency of the emitted photon:

Where h is the Planck constant. The photon's frequency is inversely proportional to its wavelegth:

Here c is the speed of light. Replacing (2) in (1):

If the angle is either 0 or 180, that means that there is either negative or positive work, so A and D are not correct.
If the angle is 45, then there is still some work involved.
The only option where there is no work done by a force is B. when the angle is between the force and displacement is 90.
Answer: 75.02 m
Explanation:
u = 0 ( starts from rest )
v = 50 m/s
t = 3 s
( i ) a = v - u / t
= 50 - 0 /3
= 16.67
( ii ) s = ut + 1/2 at²
= 0 × 3 + 1/2 × 16.67 × 3 × 3
= <u>75.02 m</u>
Hope this helps...