Answer:
The time taken for the ball to return to the starting point is is 7.4 s
Explanation:
Given;
initial velocity of the ball, u = 36 m/s
the final vellocity at maximum height, v = 0
let time taken for the ball to reach maxmimum height = t
Time taken for the ball to return to the starting point is known as time of flight, calculated as;
T = (2 x 36) / 9.8
T = 7.4 s
Therefore, the time taken for the ball to return to the starting point is is 7.4 s
Answer:
for the birds to be able to stay vertical in flight without falling down to earth, they must produce a lift that will counteract their weight
for the small bee humming bird,
mass = 1.6 g = 1.6 x kg
weight of the bird under acceleration due to gravity = mg
where g = acceleration due to gravity = 9.81 m/s^2
weight of the bird = 1.6 x x 9.806 = 0.0156 ≅ 0.016 N
for this bird to maintain flight, the least lift upward, it must generate must be equal to its weight downwards, i.e
lift = weight
therefore,
lift = <em>0.016 N</em>
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For the bustard of Europe and Asia,
mass = 21 kg
weight of the bird under acceleration due to gravity = mg
weight of the bird = 21 x 9.806 = 205.9 N
lift = weight = <em>205.9 N</em>
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<em>lift generated is proportional to the wing surface area according to the lift equation</em>
L = Cs x p x x S
where L = lift
C = lift coefficient
p = density of air
v = relative velocity of bird and air
S = surface are of the wing.
<em>The great bustard will have a proportionally larger wing area to hold its weight in flight</em>
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Answer:
Average speed of car will be 48 km/hr
Explanation:
Let the total distance is 2d
It is given that first half of the distance car travels with a speed of 40 km/hr
So time taken to cover half of the distance
Second half of the distance is covered with a 60 km/hr
So time taken to cover second half of the distance
So total time to cover 2d distance
Average speed is the ratio of total distance to total time
So average speed
So average speed of car will be 48 km/hr