Answer:
135 m
Explanation:
Given:
vi = 12 m/s
vf = 18 m/s
t = 9s
Find: x
x = ½ (vf + vi) t
x = ½ (18 m/s + 12 m/s) (9 s)
x = 135 m
The answer is A
Theory- a hypothesis or an educated guess that has yet to be proven by experiment<span />
Answer:

Explanation:
The kinetic energy of a rigid body that travels at a speed v is given by the expression:

The equivalence between mass and energy established by the theory of relativity is given by:

This formula states that the equivalent energy
can be calculated as the mass
multiplied by the speed of light
squared.
Where
is approximately 
Hence:


Therefore, the ratio of the person's relativistic kinetic energy to the person's classical kinetic energy is:

Answer:
the speed of the first spacecraft as viewed from the second spacecraft is 0.95c
Explanation:
Given that;
speed of the first spacecraft from earth v
= 0.80c
speed of the second spacecraft from earth v
= -0.60 c
Using the formula for relative motion in relativistic mechanics
u' = ( v
- v
) / ( 1 - (v
v
/ c²) )
we substitute
u' = ( 0.80c - ( -0.60c) ) / ( 1 - ( ( 0.80c × -0.60c) / c² ) )
u' = ( 0.80c + 0.60c ) / ( 1 - ( -0.48c² / c² ) )
u' = 1.4c / ( 1 - ( -0.48 ) )
u' = 1.4c / ( 1 + 0.48 )
u' = 1.4c / 1.48
u' = 0.9459c ≈ 0.95c { two decimal places }
Therefore, the speed of the first spacecraft as viewed from the second spacecraft is 0.95c