When a loose brick is resting on a wall, it has energy. When the brick is pushed off the wall and is falling down, the amount of
2 answers:
The complete sentence is as follows:
When a loose brick is resting on a wall, it has potential energy. When the brick is pushed off the wall and is falling down, the amount of potential energy is decreasing while the amount of kinetic energy is increasing.
Explanation:
- Potential energy is the energy related to the position of an object: in particular, gravitational potential energy is given by
where m is the mass of the object, g is the gravitational acceleration, and h is the height of the object above the ground.
- Kinetic energy is the energy related to the motion of an object, and it is given by
where m is the mass and v the speed of the object.
In the example, we see that:
- at the beginning, the brick is at rest on the wall, so it only has potential energy due to its height above the ground (while the kinetic energy is zero, since it is at rest, so speed v is zero)
- as it falls down, the potential energy decreases, because the height h decreases, while the kinetic energy increases, because the speed of the object increases as it falls down.
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Answer:
The maximum height reached is 4.63 m.
Explanation:
Given:
Initial speed of the man (u) = 31.0 m/s
Speed at the top of trajectory () = 29.5 m/s
Acceleration due to gravity (g) = 9.8 m/s²
When the man reaches the top of the trajectory, the vertical component of velocity becomes zero and hence only horizontal component of velocity acts on him.
Also, since there is no net force acting in the horizontal direction, the acceleration is zero in the horizontal direction from Newton's second law. Thus, the horizontal component of velocity always remains the same.
So, speed at the top of trajectory is nothing but the horizontal component of initial velocity.
Now, initial velocity can be rewritten in terms of its components as:
Where, are the initial horizontal and vertical velocities of the man.
Now, plug in the given values and simplify. This gives,
Now, we know that, for a projectile motion, the maximum height is given as:
Plug in the value from equation (1) and 9.8 for 'g' to solve for 'H'. This gives,
Therefore, the maximum height reached is 4.63 m.
The magnetic north pole of the earth's magnet is in the geographic south pole.
- There are two magnetic and geographic poles each, north and south
- The two geographic poles are the locations where the earth's axis of rotation passes through which is imaginary
- The magnetic north and south poles are not the same as the geographic north and south poles
- In a compass, the needle points to the magnetic north pole
- By convention, the magnetic north pole corresponds to the geographic south pole
- The magnetic south pole corresponds to the geographic north pole
- The magnetic field lines of a magnet start from the magnetic north pole and end at the magnetic south pole
The magnetic north pole of the earth's magnet is the geographic south pole.
Learn more about earth's magnetism here:
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Answer:
21.35 cm^3
Explanation:
let the volume at the surface of fresh water is V.
The volume at a depth of 100 m is V' = 2 cm^3
temperature remains constant.
density of water, d = 1000 kg/m^3
Pressure at the surface of fresh water is atmospheric pressure,
P = Po = 1.013 x 10^5 N/m^2
The pressure at depth 100 m is P' = Po + hdg
P' =
P' = 10.813 x 10^5 N/m^2
Use the Boyle's law
P V = P' V'
V = 21.35 cm^3
Thus, the volume of air bubble at the surface of fresh water is 21.35 cm^3.