Answer:
option 4
Explanation:
Light's velocity in air ( 3 × 10^8 m/s ) is much greater than sound's velocity in air ( 343 m/s )
Hence due to difference in velocities , during lightning light is seen first & sound is heard later
Answer:
number of quantum states = 8
Explanation:
To find the total number of allowed states you take into account the following relations:
in this case you have:
furthermore, for each n,l,ml quantum state you have two additional states due to the spin of the electrons.
then, you have (n,l,ml) = (2,0,0), (2,1,-1), (2,1,0), (2,1,1) and with the spin:
number of quantum states = 2*(1+3) = 8
When the object is at rest, there is a zero net force due the cancellation of the object's weight <em>w</em> with the normal force <em>n</em> of the table pushing up on the object, so that by Newton's second law,
∑ <em>F</em> = <em>n</em> - <em>w</em> = 0 → <em>n</em> = <em>w</em> = <em>mg</em> = 112.5 N ≈ 113 N
where <em>m</em> = 12.5 kg and <em>g</em> = 9.80 m/s².
The minimum force <em>F</em> needed to overcome <u>maximum</u> static friction <em>f</em> and get the object moving is
<em>F</em> > <em>f</em> = 0.50 <em>n</em> = 61.25 N ≈ 61.3 N
which means a push of <em>F</em> = 15 N is not enough the get object moving and so it stays at rest in equilibrium. While the push is being done, the net force on the object is still zero, but now the horizontal push and static friction cancel each other.
So:
(a) Your free body diagram should show the object with 4 forces acting on it as described above. You have to draw it to scale, so whatever length you use for the normal force and weight vectors, the length of the push and static friction vectors should be about 61.3/112.5 ≈ 0.545 ≈ 54.5% as long.
(b) Friction has a magnitude of 15 N because it balances the pushing force.
(c) The object is in equilibrium and not moving, so the acceleration is zero.
Answer:
<h3>t = 100secs</h3>
Explanation:
The following data
Distance x = 17km = 17000m
Speed v = 340m/s
Using the formula to get the time;
2x = vt
t = 2x/v
t = 2(17000)/340
t = 34000/340
t = 100secs
<em>Hence it takes 100seconds for the sound to reach your ears</em>
