Which of the following statements is true about scientific theories?

A cup of coffee is sitting on a table in a train that is moving with a constant velocity. The coefficient of static friction bet

Vikki [24]

Answer:

a = 2.94 m/s²

Explanation:

In order for the cup not to slip, the unbalanced force on cup must be equal to the frictional force:

Unbalanced Force = Frictional Force

ma = μR = μW

ma = μmg

a = μg

where,

a = maximum acceleration for the cup not to slip = ?

μ = coefficient of static friction = 0.3

g = acceleration due to gravity = 9.8 m/s²

Therefore,

a = (0.3)(9.8 m/s²)

3 0

2 years ago

A long thin uniform rod of length 1.50 m is to be suspended from a frictionless pivot located at some point along the rod so tha

Dvinal [7]

Answer:

0.087 m

Explanation:

Length of the rod, L = 1.5 m

Let the mass of the rod is m and d is the distance between the pivot point and the centre of mass.

time period, T = 3 s

the formula for the time period of the pendulum is given by

$T = 2\pi \sqrt{\frac{I}{mgd}}$ .... (1)

where, I is the moment of inertia of the rod about the pivot point and g is the acceleration due to gravity.

Moment of inertia of the rod about the centre of mass, Ic = mL²/12

By using the parallel axis theorem, the moment of inertia of the rod about the pivot is

I = Ic + md²

$I = \frac{mL^{2}}{12}+ md^{2}$

Substituting the values in equation (1)

$3 = 2 \pi \sqrt{\frac{\frac{mL^{2}}{12}+ md^{2}}{mgd}}$

$9=4\pi^{2}\times \left ( \frac{\frac{L^{2}}{12}+d^{2}}{gd} \right )$

12d² -26.84 d + 2.25 = 0

$d=\frac{26.84\pm \sqrt{26.84^{2}-4\times 12\times 2.25}}{24}$

$d=\frac{26.84\pm 24.75}{24}$

d = 2.15 m , 0.087 m

d cannot be more than L/2, so the value of d is 0.087 m.

Thus, the distance between the pivot and the centre of mass of the rod is 0.087 m.

3 0

2 years ago

A light source radiates 60.0 W of single-wavelength sinusoidal light uniformly in all directions. What is the amplitude of the m

Anna35 [415]

To solve this problem it is necessary to take into account the concepts of Intensity as a function of Power and the definition of magnetic field.

The intensity depending on the power is defined as

$I = \frac{P}{4\pi r^2},$

Where

P = Power

r = Radius

Replacing the values that we have,

$I = \frac{60}{(4*\pi (0.7)^2)}$

$I = 9.75 Watt/m^2$

The definition of intensity tells us that,

$I = \frac{1}{2}\frac{B_o^2 c}{\mu}$

Where,

$B_0 =$ Magnetic field

$\mu =$ Permeability constant

c = Speed velocity

Then replacing with our values we have,

$9.75 = \frac{Bo^2 (3*10^8)}{(4\pi*10^{-7})}$

Re-arrange to find the magnetic Field B_0

$B_o = 2.86*10^{-7} T$

Therefore the amplitude of the magnetic field of this light is $B_o = 2.86*10^{-7} T$

6 0

3 years ago

The coefficient of kinetic friction between an object and the surface upon which it is sliding is 0. 10. The mass of the object

lilavasa [31]

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:

$F_{f} =$ μ * $F_{n}$

where,

$F_{f}$ = force of friction

μ = coefficient of friction

$F_{n}$ = normal force

Given,

μ $= 0.10, m = 8.0 kg$

We know,

$F_{n} = mg$

$F_{n} = 8.0 * 9.8\\\\ F_{n} = 78.4 N$

Subsituing the values in equation:

$F_{f} =$ μ * $F_{n}$

$F_{f} = 0.10 * 78.4 \\\\F_{f} = 7.84 N$

The force of friction is 78.4 N.

To know more about force of friction, check out:

brainly.com/question/24386803

#SPJ4

4 0

9 months ago

Two sticks are suspended on silk thread, electrified by charges of opposite sign. Is there a magnetic field around them? An elec

IRINA_888 [86]

ANSWER and EXPLANATION

We want to identify if there will be an electric field and a magnetic field around the two sticks electrified by charges of opposite signs.

An electric field is a physical field that surrounds electrically charged particles and exerts a force on other charged particles in the surrounding.

This implies that the presence of electric charges on both sticks generates electric fields on them. Since the two charges are opposite, the electric force acting on them will be attractive.

Hence, there is an electric field.

A stationary charged object produces an electric field, as explained above, but will only produce a magnetic field if there is a motion of the object.

Hence, except the two sticks are caused to move, there will be no magnetic field around them.

5 0

1 year ago