Hello, love! The answer is True, or T, on Edge2020.
Hope this helped!
~ V.
Answer:
(a) 
(b) P = 0.816 Watt
Explanation:
(a)
The power radiated from a black body is given by Stefan Boltzman Law:

where,
P = Energy Radiated per Second = ?
σ = stefan boltzman constant = 5.67 x 10⁻⁸ W/m².K⁴
T = Absolute Temperature
So the ratio of power at 250 K to the power at 2000 K is given as:

(b)
Now, for 90% radiator blackbody at 2000 K:

<u>P = 0.816 Watt</u>
Answer:
positive
Explanation:
The ball is rolling down with a negative velocity, but the velocity is slowing down. therefore the velocity must increase in order for the ball to slow down.
For example let the ball's initial velocity be -15 m/s. and it is slowing down to let's say -13 m/s. Well this means that it's velocity has increase by 2 m/s. So, its acceleration is positive.
speed of the car = 27 m/s
speed of truck ahead = 10 m/s
relative speed of car with respect to truck

relative deceleration of car

now the distance before they stop with respect to each other is given by



so it will come at the same speed of truck after 20.6 m distance and hence it will not hit the truck as the distance of the truck is 25 m from car
Part b)
Distance traveled by car before it stops is given by



so it will stop after it will cover total 52.1 m distance
Part c)
time taken by the car to stop



now the distance covered by truck in same time

now after the car will stop its distance from the truck is

<em>so the distance between them is 11.5 m</em>