Answer:
No, there wasn't any variation in the light intensity at 360 degrees.
During the rotation, rotating through an angle of 90° gradually brought the intensity to a maximum. Rotating by another 90° degrees brought the intensity to a minimum at some point. Rotating by another 90° brought it back to its maximum and then another 90° brought it to its initial intensity.
B you will see the objective outside the vehicle not moving will’l you are moveing inside the vehicle
Let
V the speed of the girl per step
v the speed of the escalator per step
L the length between ground and floor in number of steps
V*60+v*60=L => V+v=L/60
V*90-v*90=L => V-v=L/90
By adding the equations V+v=L/60 and V-v=L/90 we get:
2V=L(3+2)/180
V=5L/360
V = L/72
Time to climb (in steps) with v=0 (escalator standing still) is:
V*t=L
t = L/V
t = L/(L/72)
t =72 steps
The girl will count 72 steps.
Answer:
A, B and D
2. A
Explanation:
1.Which of the following statements about light waves is true? check all correct answers
A.They come from sources across space reason is that a light can travels form its source and its moves across the space
B.They travel in a straight line from their source reason is that the type of light that undergo these is called parallel ray of light
C.They can travel through any type of material reason not all materials light can penetrate through e.g wall
D.They can be reflected by some types of material reason is that some materals reflect light rays e.g polished mirror
