Answer:
i. + 22.5 m ii. 4.0 m
Explanation:
i. Image distance
Using the lens formula
1/u + 1/v = 1/f where f = focal length = + 18.0 m, u = object distance = distance of shark away from lens = + 90.0 m and v = image distance from lens = unknown
So, we find v
1/v = 1/f - 1/u
= 1/+18 - 1/+90
= (5 - 1)/90
= 4/90
v = 90/4
= + 22.5 m
So the image is real and formed 22.5 m away on the other side of the lens.
ii Length of Shark
Using the magnification formula, m = image height/object height = image distance/object distance. image height = 1.0 m where object height = length of shark.
m = image distance/object distance
= v/u
= +22.5/+90
= 0.25
0.25 = image height/object height
So,
object height = image height/0.25
= 1.0 m/0.25
= 4.0 m
So, the length of the shark is 4.0 m
As we know that it has all given data given as
distance moved = 0.250 km = 250 m
now we can use kinematics to find acceleration
so it will accelerate at rate of 0.86 m/s^2
Here are two ways to do it:
<u>Way #1:</u>
-- You know that gravity accelerates things that are falling freely, adding 9.8 m/s to their speed every second.
-- After 6 seconds, an object that fell from rest winds up falling at (9.8 x 6) = 58.8m/s.
-- During that time, its average speed was 1/2(0 + 58.8) = 29.4 m/s .
-- In 6 seconds, at an average speed of 29.4 m/s, it covers (29.4 x 6) = <em>176.4meters</em>.
<u>Way #2:</u>
This way only works if you remember the formula for the distance covered during uniform acceleration.
D = 1/2 (acceleration) (time)²
Acceleration = gravity = 9.8 m/s²
Time = 6 seconds
D = 1/2 (9.8) (6)² = <em>176.4 meters</em>.
