Answer:
49 N
Explanation:
In order to move the box at constant speed, the acceleration of the box must be zero (a=0): this means, according to Newton's second law,
F = ma
that the net force acting on the box, F, must be zero as well.
Here there are two forces acting on the box in the horizontal direction while it is moving:
- The force of push applied by the guy, F
- The frictional force, 
For an object moving on a flat surface, the frictional force is given by

where
is the coefficient of friction
m is the mass of the box
g is the acceleration of gravity
So the equation of the forces becomes

And substituting:

We find the force that must be applied by the guy:

Answer:
10.99 m
Explanation:
m = mass of the block = 0.245 kg
k = spring constant of the vertical spring = 4975 N/m
x = compression of the spring = 0.103 m
h = height to which the block rise
Using conservation of energy
Potential energy gained by the block = Spring potential energy
mgh = (0.5) k x²
(0.245) (9.8) h = (0.5) (4975) (0.103)²
h = 10.99 m
Could u put it in english u can use goggle translation if u do not know how to
Explanation:
Formula to calculate angular acceleration is as follows.

or, 
Putting the given values into the above formula as follows.

=
= 0.326 
Thus, we can conclude that the wheel’s angular acceleration if its initial angular speed is 2.5 rad/s is 0.326
.
The potential at a distance r from a charge Q is given by

where ke is the Coulomb's constant.
The charge in our problem is

; for the point at

, the potential is

For the point at infinity, we immediately see that the potential is zero, because

and so

.
Therefore, the potential difference between the two points is