What does it mean when we say a scientific question must be testable?

Ksju [112]

1. False

Explanation: it's exactly the opposite. In fact, Lenz's law states that the induced current and the induced emf in a conductor are generated in such a direction that opposes to the change in magnetic flux through the coil. This is summarized by the negative sign in the Faraday's Newmann Lenz law:

$\epsilon= -\frac{d\Phi }{dt}$

where $\epsilon$ is the emf induced and $\frac{d\Phi}{dt}$ is the rate of change of magnetic flux through the coil.

Lenz's law is a consequence of the law of conservation of energy. In fact, we have:

- If the magnetic flux through a coil is increasing, then the induced current has a direction such that the magnetic field generated by the coil is opposite to the direction of the external magnetic field, in order to decrease the total flux

- If the magnetic flux through a coil is decreasing, then the induced current has a direction such that the magnetic field generated by the coil is in the same direction as the external field, in order to increase the total flux

2. False

Explanation: the magnetic flux through a surface is given by

$\Phi = BA cos \theta$

where

B is the magnitude of the magnetic field

A is the surface area

$\theta$ is the angle between the direction of B and the normal vector to the surface

As we see, the magnetic flux depends not only on B and A, but also on the orientation of the coil with respect to the magnetic field.

3. False

Explanation:

- Sound waves are mechanical waves: mechanical waves are waves consisting of oscillations of the particles in a medium. Due to their nature, therefore, mechanical waves can propagate only in the presence of a medium

- Electromagnetic waves are NOT mechanical waves: they consist of oscillations of electric and magnetic fields, in a direction perpendicular to the direction of propagation of the wave. Since em waves are not mechanical waves, they do NOT need a medium to propagate, since they can also travel through a vacuum; therefore the original statement is false.

5 0

3 years ago

Rhea is a high school gymnast, and she is really inspired by Simone Biles. Rhea really admires her skill and dedication. However

Alborosie

Answer: D

Explanation:

If Rhea is inspired and not too focused on comparing abilities, Biles is a good role model.

6 0

3 years ago

Which countries were considered the three major Axis Powers?

wariber [46]

The main Axis powers were Germany, Japan and Italy. The Axis leaders were Adolf Hitler (Germany), Benito Mussolini (Italy), and Emperor Hirohito (Japan)

4 0

3 years ago

A 45.0 kg girl is standing on a 159 kg plank. The plank, originally at rest, is free to slide on a frozen lake, which is a flat,

Ganezh [65]

Answer:

(a) $v_g_i=1.08\frac{m}{s}$

(b) $v_p_i=-0.3\frac{m}{s}$

Explanation:

According to the law of conservation of momentum:

$\Delta p=0\\p_i=p_f$

Initially, the girl and the plank are at rest. So, relative to the ice, we have:

$0=m_gv_g_i+m_pv_p_i\\v_p_i=-\frac{m_gv_g_i}{m_p_i}(1)$

(a) The velocity of the girl relative to the ice is:

$v_g_i=v_g_p+v_p_i(2)$

Here, $v_g_p$ is the velocity of the girl relative to the plank and $v_p_i$ is the velocity of the plank relative to the ice.

Replacing (1) in (2):

$v_g_i=v_g_p-\frac{m_gv_g_i}{m_p_i}\\v_g_i+\frac{m_gv_g_i}{m_p_i}=v_g_p\\v_g_i(1+\frac{m_g}{m_p})=v_g_p\\v_g_i=\frac{v_g_p}{1+\frac{m_g}{m_p}}\\v_g_i=\frac{1.38\frac{m}{s}}{1+\frac{45kg}{159kg}}\\v_g_i=1.08\frac{m}{s}$

(b) According to (2), the velocity of the plank relative to the surface of ice is:

$v_p_i=v_g_i-v_g_p\\v_p_i=1.08\frac{m}{s}-1.38\frac{m}{s}\\v_p_i=-0.3\frac{m}{s}$

The negative sing indicates that the plank is moving to the left.

3 0

3 years ago

Is a bike standing still potential or kinetic?

BartSMP [9]

Answer:

potential

Explanation:

Potential energy is stored

Plz mark brainliest

6 0

3 years ago