<h3><u>Answer;</u></h3>
= 75 %
<h3><u>Explanation</u>;</h3>
To measure efficiency of a machine, compare the work output to work input.
Efficiency = Work output/ work output × 100 %
= 300/400 × 100
= 75 %
Yes, the answer is in fact C. All of the above.
Variable stars are stars that change in brightness. The change could be due to the physical change in the star or it could also be caused when another star crosses another, or in other words eclipse.
Answer:
The key point was that Kennedy challenged Nixon to a series of televised debates. It was the first televised presidential debate in American history.
In 1960, 88 % of American homes had television. About 2/3 of the electorate watched the first debate on TV. Nixon was recovering from a knee injury, he looked drained. Kennedy, meanwhile, had been resting in a hotel for an entire weekend, he looked tan and confident.
Most Americans watching the debates voted for Kennedy, most radio listeners seemed to give the edge to Nixon. hope this helps
Answer:
a=3.53 m/s^2
Explanation:
Vo=0 m/s (because he is not moving at the start)
V1=15 m/s
t= 4.25 s
a = (V1-Vo) / t = 15/4.25 = 3.53 m/s^2
Answer:
1.) h = 164.8 m
2.) U = 49.1 m/s
3.) t = 1.43 seconds
Explanation:
1.) A soccer ball is dropped from the top of a building. It takes 5.8 seconds to fall to the ground. The height of the building is...?
Since the soccer ball is dropped from the building, the initial velocity U will be equal to zero
Using second equation of motion
h = Ut + 1/2gt^2
Substitutes the time into the formula
h = 1/2 × 9.8 × 5.8^2
h = 164.8 m
2. The Falcon 9 launches to a height of 123 meters. What is its vertical initial velocity?
At maximum height final velocity = 0
Using the third law of motion
V^2 = U^2 - 2gH
0 = U^2 - 2 × 9.8 × 123
U^2 = 2410.8
U = 49.1 m/s
3. An apple falls from rest off a 10.m m tree. How long will it take before it hits the ground?
Since the apple fall from rest, the initial velocity U will be equal to zero
Using the second equation of motion,
h = Ut + 1/2gt^2
substitute all the parameters into the formula
10 = 1/2 × 9.8 × t^2
10 = 4.9t^2
t^2 = 10/4.9
t^2 = 2.04
t = 1.43 seconds
