I'm assuming you mean models of the solar system:
Both Aristotle and Ptolemy had the idea that the solar system was geocentric. This means that all objects in the solar system including the Sun revolve around the Earth.
Answer:
The answer is D.
Explanation:
One explanation I can give you is that generally waves travel faster through denser medium because the particles are tightly packed together and so they can transfer energy faster. But to verify the answer, I used Process of Elimination because the other 3 answers are not true. Choice A is entirely true, wave speed depends on the medium it is travelling through, so there is no way choice A is correct. Choice B is wrong because for example if we take light(an EM wave), it travels at a constant speed of 3.0x10^8 m/s in a vacuum and in open space. So, that proves that air or vacuum do not affect the speed of the wave in another medium. Choice C is related to Choice B, we just proved the speed of light is constant everywhere whereas choice C says that in a vacuum the speed is halved. Good luck in your Physics class and I hope for your best!
If you use the stairs at normal speed, you will survive longer, and go up higher.
When going up the stairs twice as fast, you lose energy more quickly, but height would remain the same.
Answer:
- The impulse exerted by the ball is 7.2 kg.m/s
- The average force exerted on the ball by the bat is 600 N.
Explanation:
Given;
mass of the baseball, m = 0.144 kg
velocity of the baseball, v₁ = 20 m/s
velocity of the batter, v₂ = -30 m/s (opposite direction to the ball's speed)
The impulse exerted by the ball is calculated as follows;
J = ΔP = mv₁ - mv₂
ΔP = m(v₁ - v₂)
ΔP = 0.144 [20 - (-30)]
ΔP = 0.144 ( 20 + 30 )
ΔP = 0.144 (50)
ΔP = 7.2 kg.m/s
The average force exerted on the ball by the bat is calculated as;
Answer:
0.765m
Explanation:
gravitational potential energy GPE = mass * acceleration due to gravity * height
Given
GPE = 30Joules
Mass m = 4kg
acceleration = 9.8m/s²
Required
Height h
From the formula
h = GPE/mg
h = 30/4(9.8)
h = 30/39.2
h = 0.765m\
Hence the height of the counter is 0.765m
