Answer:

Explanation:
Given that,
The car traveled a total of 1,200 meters during this test.
We need to find the average speed of the car. The average speed of the car is given by total distance covered divided by the time taken. So,

But putting the value of t we can find the average speed of the car.
Answer:
Explanation:
Given ,
dv / dt = k ( 160 - v )
dv / ( 160 - v ) = kdt
ln ( 160 - v ) = kt + c , where c is a constant
when t = 0 , v = 0
Putting the values , we have
c = ln 160
ln ( 160 - v ) = kt + ln 160
ln ( 160 - v / 160 ) = kt
(160 - v ) / 160 = 
1 - v / 160 = 
v / 160 = 1 - 
v = 160 ( 1 -
)
differentiating ,
dv / dt = - 160k 
acceleration a = - 160k 
given when t = 0 , a = 280
280 = - 160 k
k = - 175
a = - 160 x - 175 
a = 28000 
when a = 128 t = ?
128 = 28000 
= .00457
The first telescopes were refracting telescopes ... a tube
with lenses at both ends. The quality of the image depends
on the quality of both lenses, because the light must pass
through both of them.
The reflecting telescope was an improvement, because the
light doesn't have to go through the mirror. The quality of the
primary mirror only depends on the shape and shinyness of
its surface.
If you could carve an optically perfect parabolic surface out of
a piece of wood and coat it with a thin layer of shiny silver, then
you could use a log to make a good reflecting telescope.
II seem to recall that Newton made one out of brass !