Answer:
-7.14
Explanation:
According to equation of motion
v = u + at
where
v is the final velocity at any time t
u is the initial velocity
a is the acceleration
and t is the time
___________________________________________
Given
An object is thrown upward it means
its initial velocity is in upward direction
but acceleration due to gravity is in downward direction which will cause to decrease the velocity of object.
Intial velocity u = 31.1 m/s
final velocity v at 4 second we have to find.
t = 4 second
a = g = 9.81 m/s2 (it is acting in opposite direction of motion hence its sign will be negative ).
Thus
a = - 9.81 m/s2
using the above values in v = u + at
v = 32.1 - 9.81*4
v = 32.1 - 39.24
v = -7.14
Thus, correct option is -7.14.
Answer:

13.009503 C
Explanation:
= Permittivity of free space = 
k = Dielectric constant of air 
Side of plate = 0.7 km
A = Area
d = Distance = 650 m
Capacitance is given by

The capacitance is 
Electric field is given by

The charge on the cloud is 13.009503 C
The force that acts on all objects, all the time on Earth is gravitational force.
The force that surface exert on an object perpendicularly is normal reaction.
<h3>What force acts on all objects, all the time on Earth?</h3>
- Force due to gravity is gravitational pull on objects due to its position on earth's surface.
The force due to gravity on object's is calculated by applying Newton's second law of motion as follows;
F = mg
where;
- m is the mass of the object
- g is acceleration due to gravity
The force that surface exert on an object perpendicularly is normal reaction.
Thus, the force that acts on all objects, all the time on Earth is gravitational force.
Learn more about force of gravity here: brainly.com/question/2537310
Answer:
It is called a surface wave (rayleigh wave) that transmits its energy with the wind blowing onto its surface.Hope this helps
B.a push or pull(which of the following best describes force)