Static Friction
It is the friction that exists between a stationary object and the surface on which it's resting.
Sliding friction
It is the resistance created by two objects sliding against each other.
Rolling friction:-
It is the force resisting the motion when a body rolls on a surface.
hope this helps x
Answer : The volume of a sample of 4.00 mol of copper is 
Explanation :
First we have to calculate the mass of copper.


Now we have to calculate the volume of copper.
Formula used :

Now put all the given values in this formula, we get:


Conversion used :

Therefore, the volume of a sample of 4.00 mol of copper is 
Answer:
upward force acting = 261.6 N
Explanation:
given,
mass of gibbon = 9.4 kg
arm length = 0.6 m
speed of the swing
net force must provide

force of gravity = - mg

= 
= 
=9 x 29.067
= 261.6 N
upward force acting = 261.6 N