Answer: A) because forces are what stop and start motion
Explanation:
From Newton's first law, an object tends to stay in state of rest or motion unless acted upon by an unbalanced external force. This is also known law of inertia. This is because a force can stop or start a motion. A force cause body to accelerate to decelerate otherwise the body continues with constant speed.
Answer:
- a.

- b.

- c.

Explanation:
The spacetime interval
is given by

please, be aware this is the definition for the signature ( + - - - ), for the signature (- + + + ) the spacetime interval is given by:
.
Lets work with the signature ( + - - - ), and, if needed in the other signature, we can multiply our interval by -1.
<h3>a.</h3>





so


<h3>b.</h3>





so


<h3>c.</h3>





so


Answer:
A
Explanation:
A. The pencil is on the table in broad daylight
Answer:We have , a relation in frequency f and wavelength λ of a wave having the velocity v as ,
v=fλ ,
given f=60Hz , λ=20m ,
therefore velocity of wave , v=60×20=1200m/s