Answer:
It is called force of friction
Explanation:
The force of friction is a force that acts between two objects whose surfaces are in contact with each other.
Consider the typical case of an object sliding along a certain surface. There are two types of frictions:
- Static friction: this is the force of friction that acts when the object is not in motion yet. If you push the object forward with a force F, the object will not move immediately, but it will "oppose" to this motion with a force of static friction exactly equal to the push applied:

However, this force of static friction has a maximum value, which is given by

where
is the coefficient of static friction
N is the normal reaction exerted by the surface on the object
So, when
becomes greater than
, the static friction is no longer able to balance the push applied, and the object will start sliding forward.
- Kinetic friction: this is the force of friction that acts when the object is already in motion. Its magnitude is given by

where
is the coefficient of kinetic friction, and its value is generally smaller than
. The direction of this force is also opposite to the direction of motion of the object.
Answer:
electric flux through the three side = 2.35 N m²/C
Explanation:
given,
equilateral triangle of base = 25 cm
electric field strength = 260 N/C
Area of triangle = 
= 
= 0.0271 m³
electric flux = E. A
= 260 × 0.0271
= 7.046 N m²/C
since, tetrahedron does not enclose any charge so, net flux through tetrahedron is zero.
electric flux through the three side = (electric flux through base)/3
= 
electric flux through the three side = 2.35 N m²/C
<h3>It takes 60 seconds to do the work</h3>
<em><u>Solution:</u></em>
Given that,
Force = 100 newtons
Distance = 15 meters
Power = 25 watts
To find: time it takes to do the work
<em><u>Find the work done:</u></em>

<em><u>Find the time taken</u></em>

Thus it takes 60 seconds to do the work
The speed of the car is exactly 150/7200 km/sec, or 125/6 meters/sec.
In more familiar units, that speed is equivalent to ...
-- (20 and 5/6) meters/sec
-- 75 km/hour