13.06m
Explanation:
Given parameters:
initial velocity u = 0
final velocity v = 16m/s
Unknown;
height of the hill = ?
Solution:
We are going to apply one of the laws of motion to solve this problem;
V² = U² + 2gH
where V is the final velocity
U is the initial velocity
g is the acceleration due to gravity = 9.8m/s²
H is the height
since initial velocity is zero;
V² = 2gH
To find the height;
H = 
H =
= 13.06m
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Answer
given,
diameter of the pipe is = (14 ft)4.27 m
minimum speed of the skater must have at very top = ?
At the topmost point of the pipe the normal force will be equal to zero.
F = mg
centripetal force acting on the skateboard

equating both the force equation


r = d/2 = 14/ 2 = 7 ft
or
r = 4.27/2 = 2.135 m
g = 32 ft/s² or g = 9.8 m/s²

v = 14.96 ft/s
or

v = 4.57 m/s
Answer:
<h3>0.42s</h3>
Explanation:
Velocity = Displacement/time
Displacement of the horse is the distance covered in a specified direction
Total distance of the horse towards the right = 15m + 20m = 35m
Total distance of the horse towards the left = 4m
Displacement = Distance towards the right - Distance towards the left
Displacement = 35m-4m
Displacement = 31m
Time taken = 74seconds
substitute the values gotten into the velocity formula
average velocity = 31m/74s
average velocity = 0.42m/s
Hence the magnitude of its average velocity is 0.42s
(d) option is right answer
Answer:
3.73 * 10^16 photons/sec
Explanation:
power supply = 3.0 V
Emits 440 nm blue light
current in LED = 11 mA
efficiency of LED = 51%
<u>Calculate the number of photons per second the LED will emit </u>
first step : calculate the energy of the Photon
E = hc / λ
=( 6.62 * 10^-34 * 3 * 10^8 ) / 440 * 10^-9
= 0.0451 * 10^-17 J
Next :
Number of Photon =( power supply * efficiency * current ) / energy of photon
= ( 3 * 0.51 * 11 * 10^-3 ) / 0.0451 * 10^-17
= 3.73 * 10^16 photons/sec