The height of the Empire State Building is 318.00 meters. If a stone is dropped from the top of the building, what is the stone's velocity just before it strikes the ground?
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Answer 1
Answer:
This is a free-fall problem. This can be answered using one of the free-fall equations:
V^2 = 2gh or V = √(2gh)
Where V = velocity ; h = total height (given as 318m) ; g = acceleration due to gravity (as this is on Earth, let us use 9.8 m/s^2)
With the given values, we can substitute it into the equation directly like so:
V = √(2gh) V = √(2 x 9.8 x 318) V = √(6232.8) V = 78.94808 or approximately 78.95 m/s
Therefore the stone's velocity just before hitting the ground is 78.95 m/s.
You have a 90 W electrical appliance that is on 24 hours per day. At $0.51 per kWh, how much are you paying daily for electricity to operate this appliance?Show your calculations here:
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90 watts = 0.09 KW
Energy = (power) x (time) = (0.09) x (24) KWh
Cost = (energy) x (unit price) = (0.09 x 24) x ($0.51) = $1.10 per day (rounded)
(Those are very expensive kWh's.)
Why do we insulate houses?A. To prevent heat transfer from inside to the outside B. To allow energy to flow from inside to the outside C. To keep them cool in the winter and warm in the summer
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B to allow energy to flow from inside to the outside
What must be your average speed in order to travel 350 km in 5.15 h? *66.0 km/h 67.0 km/h 68.0 km/h 69.0 km/h
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v= s/t = 5.15/ 350 =68.0 km/h
calculate the period of a wave whose frequency is 5 Hertz and whose wavelength is one centimeter give your answer in a decimal form
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The period of the wave is the reciprocal of its frequency.
1 / (5 per second) = 0.2 second .
The wavelength is irrelevant to the period. But since you gave it to us, we can also calculate the speed of the wave.
Wave speed = (frequency) x (wavelength)
= (5 per second) x (1cm) = 5 cm per second
What is the potential energy of a 1-kilogram ball is thrown into the air with an initial velocity of 30m/sec?
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the ball thrown from height=0 potental energy(PE) =0 kinetic energy(KE) = 0.5mv^2 = 0.5(1)(30^2) = 450
at the highest point the ball does not moved, v=0 potential energy at its maximum kinetic energy = 0
Energy is conserved then total energy before = after PE1 + KE1 = PE2 + KE2 0 + 450 = PE2 + 0