A doctor observe areas of pink scaly skin on patient

15. Calculate The coefficient of kinetic friction be-

allochka39001 [22]

Answer:

Wt = 26.84 [N]

Explanation:

In order to solve this problem we must use the definition of work in physics. Which tells us that this is equal to the product of force by distance.

In this case, we must sum the works of the force applied by the box and the friction force that also acts on the box.

The friction force is defined as the product of the normal force by the coefficient of friction.

f = N*μ

where:

N = normal force = m*g [N] (units of Newtons)

m = mass = 72 [kg]

g = gravity acceleration = 9.81 [m/s²]

f = friction force [N]

μ = friction coefficient = 0.21

f = 72*9.81*0.21

f = 148.32 [N]

Now the total work:

Wt = WF - Wf

where:

Wt = total work [J] (units of Joules)

WF = work by the pushing force [J]

Wf = work done by the friction force [J]

Wt = (160*2.3) - (148.32*2.3)

Wt = 26.84 [N]

Note: The friction force exerts a negative work, because this force is acting in opposite direction to the movement, therefore the negative sign.

3 0

3 years ago

If you tie a rope to a tree and move it up and down, you are creating what kind of wave?

loris [4]

This is called a<em> standing wave</em> since the waves don't move ALONG the rope. They just kind of stand in one place on the rope. if you just whip a long rope that's not tied to anything, you see the wave move along the rope, this is a TRANSVERSE wave. When you crack a qhip you send a transverse wave down the whip which concentrates in the tip, accelerating the tip to faster than the speed of sound resulting in a tiny sonic boom or "whip crack".

4 0

3 years ago

PLEASE HELP 15 POINTS The electric field around a positive charge is shown in the diagram. Describe the nature of these lines. P

DENIUS [597]

The field lines spread apart as we move away from the charge, and they point away from the charge

Explanation:

The electric field produced by a single-point positive charge is a radial field, whose strength is given by the equation

$E=k\frac{Q}{r^2}$

where

k is the Coulomb's constant

Q is the magnitude of the charge

r is the distance from the charge at which the field is calculated

There are two pieces of information given by the field lines shown in the graph:

The spacing between the lines gives an indication of the strength of the field: the closer to each other they are, the stronger the field. In this case, as we move away from the charge, the spacing between the lines increases, and this means that the field becomes weaker (in fact, it follows an inverse square law, $E\propto \frac{1}{r^2}$
The direction of the lines gives the direction of the electric field, which points away from the central charge. This is because the direction of the electric field corresponds to the direction of the force that a positive test charge would feel when immersed in the electric field: in this case, if we place a positive test charge in this field, then it would get repelled away from the central charge (remember that the electric force between two positive charges is repulsive), and therefore, the direction of the electric field is away from the central charge.