Answer:
1.contact force
2. Non contact
Explanation:
1. Because bodies are in contact
2.Bodies are not in contact.
Answer:
The distance is
Explanation:
From the question we are told that
The initial speed of the electron is 
The mass of electron is 
Let
be the distance between the electron and the proton when the speed of the electron instantaneously equal to twice the initial value
Let
be the initial kinetic energy of the electron \
Let
be the kinetic energy of the electron at the distance
from the proton
Considering that energy is conserved,
The energy at the initial position of the electron = The energy at the final position of the electron
i.e

are the potential energy at the initial position of the electron and at distance d of the electron to the proton
Here 
So the equation becomes

Here
are the charge on the electron and the proton and their are the same since a charge on an electron is equal to charge on a proton
is electrostatic constant with value 
i.e
is the velocity at distance d from the proton = 2
So the equation becomes

![\frac{1}{2} mv_i^2 = 4 [\frac{1}{2}mv_i^2 ]- \frac{k(q)^2}{d}](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B2%7D%20mv_i%5E2%20%20%3D%204%20%5B%5Cfrac%7B1%7D%7B2%7Dmv_i%5E2%20%5D-%20%5Cfrac%7Bk%28q%29%5E2%7D%7Bd%7D)
![3[\frac{1}{2}mv_i^2 ] = \frac{k(q)^2}{d}](https://tex.z-dn.net/?f=3%5B%5Cfrac%7B1%7D%7B2%7Dmv_i%5E2%20%5D%20%3D%20%5Cfrac%7Bk%28q%29%5E2%7D%7Bd%7D)
Making d the subject of the formula



The force of friction is 78.4 N
What is force of friction?
Frictional force is the force created when two surfaces come into contact and slide against each other. it is given by the equation:
μ * 
where,
= force of friction
μ = coefficient of friction
= normal force
Given,
μ 
We know,


Subsituing the values in equation:
μ * 

The force of friction is 78.4 N.
To know more about force of friction, check out:
brainly.com/question/24386803
#SPJ4
Answer:
4 seconds
Explanation:
bullet flies 200m/s. thus 800m/200m=4sec
Answer:
2nd no. positive.... 3rd no. negitive......