PLEASE HELP ME IM TIMED
1 answer:
You might be interested in
The age of the given rock is 700 million years.
The given parameters;
- <em>original mass of the rock, = 20 g</em>
- <em>mass of the rock remaining after decay, = 10 g</em>
- <em>half life of Uranium, </em>
<em> = 700 years</em>
age of the rock ----------------------------- mass remaining
0 ------------------------------------------- 20 g
1 half life ( ) ------------------------------ 10 g
Age of the rock
Thus, the age of the given rock is 700 million years.
Learn more here:brainly.com/question/23774743
Answer:
4.8 m/s
Explanation:
When she catches the train,
- They will have travelled the same distance.and
- Their speeds will be equal
The formula for the distance covered by the train is
d = ½at² = ½ × 0.40t² = 0.20t²
The passenger starts running at a constant speed 6 s later, so her formula is
d = v(t - 6.0)
The passenger and the train will have covered the same distance when she has caught it, so
(1) 0.20t² = v(t - 6.0)
The speed of the train is
v = at = 0.40t
The speed of the passenger is v.
(2) 0.40t = v
Substitute (2) into (1)
0.20t² = 0.40t(t - 6.0) = 0.40t² - 2.4 t
Subtract 0.20t² from each side
0.20t² - 2.4t = 0
Factor the quadratic
t(0.20t - 2.4) = 0
Apply the zero-product rule
t =0 0.20t - 2.4 = 0
0.20t = 2.4
(3) t = 12
We reject t = 0 s.
Substitute (3) into (2)
0.40 × 12 = v
v = 4.8 m/s
The slowest constant speed at which she can run and catch the train is 4.8 m/s.
A plot of distance vs time shows that she will catch the train 6 s after starting. Both she and the train will have travelled 28.8 m. Her average speed is 28.8 m/6 s = 4.8 m/s.
