Option B would be right one
according to momentum conservation
6600*2 = 13200kgm/s
5400*3 = 16200kgm/s
16200-13200 = 3000
now 6600-5400 = 1200 kg
thus 3000/1200 = 2.5 v
In a stationary situation, the weight of person is
This is the weight "felt" by the scale, which is basically the normal reaction applied by the scale on the person, and which uses the value of g (9.81) as reference to convert the weight (602.8 N) into a mass (62 kg).
When the person is in the elevator, the scale says 77 kg. The scale is still using the same value of conversion (9.81), so the apparent weight "felt" by the scale is
This is the normal reaction applied by the scale on the person, and which is directed upward. Besides this force, there is still the weight W of the person, acting downward. So, if we use Newton's second law:
where a is the acceleration of the elevator. If we solve for a, we find
The negative sign means the acceleration is in the opposite direction of g (which we take positive), so it means the elevator is going upward.
<span>K.E = 0.5 * m * v^2 ( m = mass(Kg), V = Velocity(m/s)
= 0.5 * 8 * 5^2
= 4 * 25
= 100 J </span>
Memorize this and you'll be able to do ALL of these: <em>1 kg = 1,000 g</em>
So if you have some grams, divide the number by 1,000 to get kilograms.
1,000 g = 1.000 kg
500 g = 0.500 kg
100 g = 0.100 kg
50 g = 0.050 kg
20 g = 0.020 kg
10 g = 0.010 kg