Answer:
Explanation:
Given
Each student exert a force of 
Let mass of car be m
there are 18 students who lifts the car
Total force by 18 students 
therefore weight of car 
mass of car 
(b)
Answer:
Any incident ray traveling parallel to the principal axis of a converging lens will refract through the lens and travel through the focal point on the opposite side of the lens. ... These rays of light will refract when they enter the lens and refract when they leave the lens.
Hope this helps...
Answer:
a) t = 4.16 s
b) x = 141.51 m
Explanation:
Given
v = 21.5 m/s
x0 = 52.0 m
a = 6.0 m/s²
a) Motorcycle
x = v0*t + (a*t²/2)
x = 21.5t + (6*t²/2)
x = 21.5t + 3t² <em>(I)</em>
Car
x = x0 + v0*t
x = 52 + 21.5t <em>(II)</em>
<em />
then we can apply <em>I = II</em>
21.5t + 3t² = 52 + 21.5t
⇒ 3t² = 52
⇒ t = 4.16 s
b) We can use <em>I</em> or <em>II</em>, then
x = 52 + 21.5*(4.16)
⇒ x = 141.51 m
Answer;
1 hectare meter is equal to 10000 cubic meter.
Density is defined as [mass] / [volume] .
The only choice listed with those physical dimensions is 'd' .
