Answer:
You need (B) Two substances in direct contact with one another to have conduction.
I hope this helped at all.
10 would be the answer for number 3
Answer:
There's a video called Drawing Position vs Time Graphs made by MrDGenova that may help you, it's only three minutes long.
Explanation:
Hope that helps, if not, you could tell me what you don't understand and I could try explaining it in further detail.
You are asked to give the answer in <span>g/cm3. So without knowing any single formulae you can just divide grams by cm3.
</span>

= 4.5 g/cm3
Answer:

Explanation:
Given that,
The length of a string, l = 0.87 m
Speed of the ball, v = 3.36 m/s
We need to find the acceleration of the ball. The acceleration acting on the ball is centripetal acceleration. It is given by :

So, the acceleration of the ball is
.