'H' = height at any time
'T' = time after both actions
'G' = acceleration of gravity
'S' = speed at the beginning of time
Let's call 'up' the positive direction.
Let's assume that the tossed stone is tossed from the ground, not from the tower.
For the stone dropped from the 50m tower:
H = +50 - (1/2) G T²
For the stone tossed upward from the ground:
H = +20T - (1/2) G T²
When the stones' paths cross, their <em>H</em>eights are equal.
50 - (1/2) G T² = 20T - (1/2) G T²
Wow ! Look at that ! Add (1/2) G T² to each side of that equation,
and all we have left is:
50 = 20T Isn't that incredible ? ! ?
Divide each side by 20 :
<u>2.5 = T</u>
The stones meet in the air 2.5 seconds after the drop/toss.
I want to see something:
What is their height, and what is the tossed stone doing, when they meet ?
Their height is +50 - (1/2) G T² = 19.375 meters
The speed of the tossed stone is +20 - (1/2) G T = +7.75 m/s ... still moving up.
I wanted to see whether the tossed stone had reached the peak of the toss,
and was falling when the dropped stone overtook it. The answer is no ... the
dropped stone was still moving up at 7.75 m/s when it met the dropped one.
A passenger weighing 500N is inside an elevator weighing 24500 N that rises 30 m every minute is 12500 W (12.5 kW).
What is Power?
Power is the amount of work that is done per unit of time. It can be associated with the speed of a change of energy within a system, or the time it takes to perform a job.
There are different types of power,
Mechanical power: is that work performed by an individual or a machine in a certain period of time.
Electric power: which is the result of the multiplication of the potential difference between the ends of a load and the current flowing there.
P= W/t
Where, P- Power,
W- Work
T- Time
The total weight of the passenger + elevator is
Fg = 500+24500
= 25000
The total work done to rise the elevator + passenger is equal to the product between the total weight and the distance covered during the trip (d = 30 m):
W = Fgd
= 25000×30
=7,50,000 J.
The power needed for the trip is equal to the ratio between the work done (W) and the time taken (t):
P = W/t
Since the time taken is t = 1 min = 60 s, the power needed is
P = 750000 / 60
= 12,500 W
P = 12.5 kW
Thus, Power was calculated as P = 12.5 kW.
Learn more about Power,
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In this case, the movement is uniformly delayed (the final
rapidity is less than the initial rapidity), therefore, the value of the
acceleration will be negative.
1. The following equation is used:
a = (Vf-Vo)/ t
a: acceleration (m/s2)
Vf: final rapidity (m/s)
Vo: initial rapidity (m/s)
t: time (s)
2. Substituting the values in the equation:
a = (5 m/s- 27 m/s)/6.87 s
3. The car's acceleration is:
a= -3.20 m/ s<span>^2</span>
Energy is the capacity of doing work
Answer:
No
Explanation:
Unless there are other external forces, this will never be true. Because according to energy conservation, potential energy will be converted to kinetic energy as the ball falls down (so it loses height and gain speed). And vice versa, kinetic to potential when it bounces back. So the potential energy after must be the same (or smaller if losing heat to external environment), so it can only get the the same height or less, but not more.