Answer:
From 0 -4 seconds the acceleration is positive. (The graph is going upwards.)
From 6-10 seconds the acceleration is negative. (The graph is going downwards.)
Explanation:
It is given that,
Radius of the circular orbit,
Speed of the electron, 
Mass of the electron, 
(a) The force acting on the electron is centripetal force. Its formula is given by :


(b) The centripetal acceleration of the electron is given by :



Hence, this is the required solution.
Answer:
b) 12.12 m/s² upwards
Explanation:
∑F = ma
21 sin 60° N = (1.5 kg) a
a = 12.12 m/s²
The less dense areas created as a sound wave propagates are called Rarefactions
Examples of medium are solid ,liquid ,and gas basically matter. :D