I believe L waves arrive last at a seismometer.
hope this helps!
Decompose the forces acting on the block into components that are parallel and perpendicular to the ramp. (See attached free body diagram. Forces are not drawn to scale)
• The net force in the parallel direction is
∑ <em>F</em> (para) = -<em>mg</em> sin(21°) - <em>f</em> = <em>ma</em>
• The net force in the perpendicular direction is
∑ <em>F</em> (perp) = <em>n</em> - <em>mg</em> cos(21°) = 0
Solving the second equation for <em>n</em> gives
<em>n</em> = <em>mg</em> cos(21°)
<em>n</em> = (0.200 kg) (9.80 m/s²) cos(21°)
<em>n</em> ≈ 1.83 N
Then the magnitude of friction is
<em>f</em> = <em>µn</em>
<em>f</em> = 0.25 (1.83 N)
<em>f</em> ≈ 0.457 N
Solve for the acceleration <em>a</em> :
-<em>mg</em> sin(21°) - <em>f</em> = <em>ma</em>
<em>a</em> = (-0.457N - (0.200 kg) (9.80 m/s²) sin(21°))/(0.200 kg)
<em>a</em> ≈ -5.80 m/s²
so the block is decelerating with magnitude
<em>a</em> = 5.80 m/s²
down the ramp.
Answer:
A force of 12.857 newtons must be applied to open the door.
Explanation:
In this case, a force is exerted on the door, a moment is performed and the door is opened. If moment remains constant, the force is inversely proportional to distance respect to axis of rotation passing through hinges. That is:

(Eq. 1)
Where:
- Force, measured in newtons.
- Proportionality ratio, measured in newton-meters.
- Distance respect to axis of rotation passing through hinges, measured in meters.
From (Eq. 1) we get the following relationship and clear the final force within:
(Eq. 2)
Where:
,
- Initial and final forces, measured in newtons.
,
- Initial and final distances, measured in meters.
If we know that
,
and
, then final force is:


A force of 12.857 newtons must be applied to open the door.
The amount of heat needed to raise the temperature of a substance by

is given by

where
m is the mass of the substance
Cs is its specific heat capacity

is the increase in temperature
For oxygen, the specific heat capacity is approximately

The variation of temperature for the sample in our problem is

while the mass is m=150 g, so the amount of heat needed is