Option C is the right answer
Answer:
a) t=1s
y = 10.1m
v=5.2m/s
b) t=1.5s
y =11.475 m
v=0.3m/s
c) t=2s
y =10.4 m
v=-4.6m/s (The minus sign (-) indicates that the ball is already going down)
Explanation:
Conceptual analysis
We apply the free fall formula for position (y) and speed (v) at any time (t).
As gravity opposes movement the sign in the equations is negative.:
y = vi*t - ½ g*t2 Equation 1
v=vit-g*t Equation 2
y: The vertical distance the ball moves at time t
vi: Initial speed
g= acceleration due to gravity
v= Speed the ball moves at time t
Known information
We know the following data:
Vi=15 m / s

t=1s ,1.5s,2s
Development of problem
We replace t in the equations (1) and (2)
a) t=1s
=15-4.9=10.1m
v=15-9.8*1 =15-9.8 =5.2m/s
b) t=1.5s
=22.5-11.025=11.475 m
v=15-9.8*1.5 =15-14.7=0.3m/s
c) t=2s
= 30-19.6=10.4 m
v=15-9.8*2 =15-19.6=-4.6m/s (The minus sign (-) indicates that the ball is already going down)
Modelling the structure of the atom is important because modeling replaces the real system with something similar but easier to examine. Option B
<h3>What is modeling?</h3>
A model is a representation of reality. We know that a model could help us to recreate reality in a manner that we could be able to relate fully with it. A model could be used also a means of explanation.
The atomic models that we have usually help us to understand more abut the atom. Therefore, modelling the structure of the atom is important because modeling replaces the real system with something similar but easier to examine. Option B
Learn more about modelling the atom:brainly.com/question/1596638
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Answer:
4.7 x 10³ rad / s
Explanation:
During the time light goes and comes back , one slot is replaced by next slot while rotating before the light source
Time taken by light to travel a distance of 2 x 500 m is
= (2 x 500) / 3 x 10⁸
= 3.333 x 10⁻⁶ s .
In this time period, two consecutive slots come before the source of light one after another by rotation. There are 400 slots so time taken to make one rotation
= 3.333 x 10⁻⁶ x 400
= 13.33 x 10⁻⁴ s
This is the time period so
T = 13.33 X 10⁻⁴
Angular speed
= 2π / T
= 
4.7 x 10³ rad / s