It's been a while since I've studied this, but my answers would be:
13. 5730 years. The half-life of a substance is the amount of time it takes for half of it to decay, and, according to the graph, half of the substance remained at 5730 years.
14. 10740 years. According to the graph, only 25% of the carbon remained after 10740 years.
15. 15 atoms. According to the graph, only 12.5% of the carbon remained after 16110 years. 12.5% of 120 atoms is 15 atoms.
16. 1600 atoms. According to the graph, if a sample of carbon is 10740 years old, only 25% of it remains. To find the original amount, multiply the current amount by (100% / 25%), which equals 4. So, 4. 400 atoms * 4 = 1600 atoms is the original amount.
Time taken by the bowling ball to reach its highest point= 0.214 s
initial velocity= Vi=2.1 m/s
Final velocity= Vf=0 as the velocity at the highest point is zero.
acceleration= g= -9.8 m/s²
using the kinematic equation Vf= Vi + at
0= 2.1 + (-9.8)t
t= -2.1/-9.8
t=0.214 s
Thus the time taken by the bowling ball to reach its highest point is 0.214 s
Explanation:
In the given question, the two metal spheres were hanged with the nylon thread.
When these two spheres were brought close together, they attracted each other. The attraction between these spheres is the result of the opposite charges between them.
The possible ways by which these two metal spheres can be charged are by induction that is touching the metal or by rubbing them.
During induction, the same charges are transferred to each sphere. In this case, either both the spheres will be negatively charged or positively charged.
It is not possible that after the sphere touch each other they will cling together because the same charge repels each other and during touching, if one sphere is neutral, then the charged one will transfer the same charge. And as we know that same charge repel each other therefore they will repel each other.
The answer to your question would be C
Force = (mass) x (acceleration)
= (0.75 kg) x (25 m/s²)
= (0.75 x 25) kg-m/s²
= 18.75 newtons .
Note that even though we're talking about a 'hit', the acceleration only
lasts as long as the bat is in contact with the ball. Once the ball leaves
the bat, it travels at whatever speed it had at the instant when they parted.
Any change in its speed or direction after that is the result of gravity, air
resistance, and the fielder's mitt. I learned a lot about these things a few
weeks ago, since I live in Chicago, about 6 miles from Wrigley Field, in
a house full of Cubs fans.
