Physical Science Pre-Test 2020-2021 Question: 1-10 The distance between Earth and the Moon was determined by measuring the time
1 answer:
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Answer: 7.38 km
Explanation: The attachment shows the illustration diagram for the question.
The range of the bomb's motion as obtained from the equations of motion,
H = u(y) t + 0.5g(t^2)
U(y) = initial vertical component of velocity = 0 m/s
That means t = √(2H/g)
The horizontal distance covered, R,
R = u(x) t = u(x) √(2H/g)
Where u(x) = the initial horizontal component of the bomb's velocity = 287 m/s, H = vertical height at which the bomb was thrown = 3.24 km = 3240 m, g = acceleration due to gravity = 9.8 m/s2
R = 287 √(2×3240/9.8) = 7380 m = 7.38 km
Given :
A bicycle racer rides from a starting marker to a turnaround marker at 10 m/s.
She then rides back along the same route from the turnaround marker to the starting marker at 25 m/s.
To Find :
Her average speed for the whole race.
Solution :
We know, average velocity is given by :
Therefore, average speed for the whole race is given by 17.5 m/s.