Answer:
Explanation:
Given
final speed v = 3015ft/s
initial speed = 0m/s
Distance S = 4146m/s
Required
Time
Using the equation of motion to get the time;
S = (v+u)/2 * t
since 1m = 3.28084ft'
4146m = 3.28084 * 4146 = 13,602.36264feet
13,602.36264 = 3015+0/2 * t
13,602.36264 = 1,507.5t
t = 13,602.36264/ 1,507.5
t = 9.023 secs
Hence it will take 9.023 seconds the rescuer die the biller to strike a target
The force of earth's gravitational field is always directed downwards (towards the center of the earth. When the ball is thrown up, it is going against the earth's gravitational field and so, the earth's gravitational force pulls it back down, accelerating it downwards.
Answer:
58.4 W
Explanation:
The speed of the lawnmower is constant: this means that its acceleration is zero, so the net force on it is zero.
The equation of the forces along the two directions therefore are:
- Perpendicular to the floor: 
- Parallel to the floor: 
where
F is the push of the gardener
R is the normal reaction
m = 20 kg is the mass
g = 9.8 m/s^2 is the acceleration of gravity
is the coefficient of friction
Solving for R,
Substituting into the other equation,
And the power he must supply therefore is the product of this force and the speed:
Answer:
0.375
Explanation:
When the 3rd sphere touches the 1st one, the charge will then be distributed between both of them, then now the 1st sphere has only half of his original charge.
In this moment then
Sphere 1 has a charge = Q/2
Sphere 3 has a charge = Q/2
When the 3rd sphere touches the 2nd sphere again the charge is distributed in a manner that both sphere has the same charge.
How the total charge is
Q = Q/2 + Q = 3/2Q,
When the spheres are separated each one has 3/4Q
Sphere 2 has a charge = 3/4Q
Sphere 3 has a charge = 3/4Q
The electrostatic force that acts on sphere 2 due to sphere 1 is:
F = (kq1q2) / r²
F = (Q/2 * 3Q/4) / r²
F = (Q² * 3) / 8r²
From the question, F = 0.42 = kQ²/r²
Thus, we can say that
F = (0.42 * 3) / 8
F = 0.1575
Thus, the ratio between F/F =
0.1575 / 0.42
Ratio, r = 0.375
Well, there you have a very important principle wrapped up in that question.
There's actually no such thing as a real, actual amount of potential energy.
There's only potential <em><u>relative to some place</u></em>. It's the work you have to do
to lift the object from that reference place to wherever it is now. It's also
the kinetic energy the object would have if it fell down to the reference place
from where it is now.
Here's the formula for potential energy: PE = (mass) x (gravity) x (<em><u>height</u></em><u>)</u> .
So naturally, when you use that formula, you need to decide "height above what ?"
If you're reading a book while you're flying in a passenger jet, the book's PE is
(M x G x 0 meters) relative to your lap, (M x G x 1 meter) relative to the floor of the
plane, (M x G x 10,000 meters) relative to the ground, and maybe (M x G x 25,000 meters)
relative to the bottom of the ocean.
Let's say that gravity is 9.8 m/s² .
Then a 4kg block sitting on the floor has (39.2 x 0 meters) PE relative to the floor
it's sitting on, also (39.2 x 3 meters) relative to the floor that's one floor downstairs,
also (39.2 x 30 meters) relative to 10 floors downstairs, and if it's on the top floor of
the Amoco/Aon Center in Chicago, maybe (39.2 x 345 meters) relative to the floor
in the coffee shop that's off the lobby on the ground floor.
