For Plato, K represents the stiffness of the spring. Hope this helps!
speed of the car at t = 10 s is given as 10 m/s
now at t = 30 s car comes to rest so v = 0
now in this velocity time graph we can say slope will show the acceleration of the car as we know that acceleration is rate of change in velocity

as we know that



now from above formula

So slope of the graph will represent the acceleration of car which is 0.5 m/s^2
Answer:
A) receding from the earth
B) 
Explanation:
- A) receding from the earth
The wavelength went from 434.1nm to 438.6nm, there was an increase in wavelength (also knowecn as redshift due to the doppler efft), this increase is due to the fact that the source that emits the radiation (the distant galaxy) is moving away and therefore the light waves it emits are "stretched", causing us to see a wavelength greater than the original.
- B)

to calculate the relative speed we use the following formula:

where
is the speed of light:
is the wavelength emited by the source, and
is the wavelength measured on earth.
we substitute all the values and do the calculations:

the relative speed is: 
Three of the statements are true. 'D' is false.
Glass and rubber are excellent insulators, total duds as conductors.
Answer:
a)V= 0.0827 m³
b)P=181.11 x 10² N/m²
Explanation:
Given that
m = 81.5 kg
Density ,ρ = 985 kg/m³
As we know that
Mass = Volume x Density
81.5 = V x 985
V= 0.0827 m³
The force exerted by weight = m g
F= m g= 81.5 x 10 = 815 N ( Take ,g= 10 m/s²)
Area ,A= 4.5 x 10⁻² m²
The Pressure P


P=181.11 x 10² N/m²