Answer:
a) 
b) 
Explanation:
Given:
mass of the ball, 
horizontal velocity of the ball, 
mass of the person, 
a)
<u>Using the law of conservation of momentum:</u>



b)
Given:
- rebound velocity of the ball,

Using conservation of momentum,



Answer:
The weak nuclear force is one of the fundamental forces:
Is a force that is responsible of some radiative phenomenoms, like the beta decay.
The intensity is way smaller than the one of the strong interaction, but this is because it acts in a way smaller range. And this can produce atractive and repulsive interactions.
So options D and B can be discarded.
And this force can be repulsive or attractive depending on the phenomena, so the options that are wrong are A and B, because the interaction is both things, not only one.
Answer:
Explanation:
Heat required to warm the water from 20 degree to 51 degree
= mct
= 131 x 4150 x ( 51 - 20 )
= 16853150 J
Power of heating element
= v² /R
Heat generated in 31 min
= (v² / r ) x 31 x 60 = 16853150
r = (240 x 240 x 31 x 60) / 16853150
6.35 ohm
In this case heat required will change so time will also change
Heat required =
131 x 4150 x ( 100-51 )
= 26638850 J
If time required be t hour
Energy consumed
Power x time
= (v² / r ) x t x 60 = 26638850
t = 26638850 x 6.35 / (240 x 240 x 60 )
= 48.95 h
Heat required to evaporate water at 100 degree
= mass x latent heat
= 131 x 2260000
= 296060000 J
Total heat required
= 296060000 + 26638850 + 16853150
= 339552000 J
time required = 339552000 x 6.35 / (240 x 240 x 60 )
= 623.88 h .
Systematic is just a certain way of doing something. So science being systematic may just refer to the scientific method or how theories are proved in science by repeating the scientific method over and over again.