I can't guess what -9.8 m/s means until you tell me where it came from,
or what 'm/s' means.
If perhaps it has something to do with the acceleration of gravity on Earth,
then the correct figure is ' -9.8 m/s² '. That means that any object that
has no other force acting on it except gravity has its speed changing by
9.8 meters per second every second. Since it's gravity doing the job,
then the object's speed is either increasing down, or decreasing up.
If an object has negative velocity, then it's moving in the direction opposite
to the direction that you decided to call positive when you started doing the
problem.
For example, if you decide that up is positive and down is negative, and
then somebody drops a stone from the top of a tall building, then the
gravitational force on the stone is negative (pointing down), its velocity
is negative (it's falling towards down), and its acceleration is negative (its
speed towards down is getting faster and faster). Everything is negative,
only because you decided that up is positive and down is negative. It's
nothing to be worried about.
The gravitational potential energy of the brick is 25.6 J
Explanation:
The gravitational potential energy of an object is the energy possessed by the object due to its position in a gravitational field.
Near the surface of a planet, the gravitational potential energy is given by
where
m is the mass of the object
g is the strength of the gravitational field
h is the height of the object relative to the ground
For the brick in this problem, we have:
m = 8 kg is its mass
g = 1.6 N/kg is the strenght of the gravitational field on the moon
h = 2 m is the height above the ground
Substituting, we find:
Learn more about potential energy:
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Answer: Heat current through the insulator=196W
Electric power= 196W
Explanation: Given: Kglass = 0.040W/m
Temperature of inside glassTi=175°C
Temperature of outside glass To= 35°C
Area=1.4m^2 , L= 4×10^-2
Heat current(H)= K ×A× (Ti - To)/L
Substituting the values into the equation
H = 0.04 × K × 1.4 ×(175-35)/4×10^-2
H= 196W.
The electric power = Heat current =196W
The electric power is the magnitude of heat current
Answer:
Explanation:
To solve this, we must know two things.
First, the force of gravity acting on an orbiting object is equal to its mass times centripetal acceleration.
Second, the force of gravity between two objects is defined by Newton's law of universal gravitation: Fg = mMG/r², where Fg is the force of gravity, m and M are the masses of the objects, G is the universal constant of gravitation, and r is the distance between the objects.
Therefore:
Fg = m v²/r
mMG/r² = m v²/r
v² = MG/r
The potential energy of each planet is:
PE = mgr = m (MG/r²) r = mMG/r
The kinetic energy of each planet is:
KE = 1/2 mv² = 1/2 m (MG/r) = 1/2 mMG/r
The total mechanical energy is:
ME = PE + KE = 3/2 mMG/r
Since both planets have the same mass, the only difference is the orbital radius. Since planet A has a smaller orbital radius, it has more potential energy, more kinetic energy, and more mechanical energy.
Answer:
magnification is - 159
objective distance is 3.85 cm
Explanation:
Given data
focal length f1 = 1.40 cm
focal length f2 = 2.20 cm
separated d = 19.6 cm
to find out
angular magnification and How far from the objective
solution
we know magnification formula that is
magnification = ( - L / f1 ) (D/f2)
here D = 25 cm put all value
magnification = ( - 19.6 / 1.40 ) (25/2.20)
magnification = - 159
and
now we apply lens formula
i/f = 1/q + 1/p
p = f2 = 2.20
so
q = f2 p / p -f2
q = 1.4(2.20) / ( 2.2 - 1.4 )
q = 3.85 cm
so objective distance is 3.85 cm
