Answer:
D and A
Explanation:
Hint The basic difference between them is that a bar magnet is a permanent magnet whereas an electromagnet is a temporary magnet. An electromagnet is formed when an electric current is passed through wires wound around soft metalcore. An electromagnet loses its magnetism once the current flow is stopped.
Answer:
537 N
Explanation:
The force due to gravity of a planet is:
F = GMm / r²
where G is the universal gravitational constant
M is the mass of the planet
m is the mass of the object
and r is the distance between the object and the center of the planet
On Earth, you weigh 716 N, so:
716 N = GMm / r²
On planet X:
F = G (3M) m / (2r)²
F = 3/4 GMm / r²
F = 3/4 (716 N)
F = 537 N
(6) first choice: the frequency appears higher and wavelength is shorter.
The car approaches a stationary observer and so the sound will appear to have shorter wavelength. This creates an effect of its siren to sound with higher frequency than it would do if both were stationary.
(7) The Doppler formula for frequency in the case of a stationary observer and source approaching it is as follows:

The wavelength is then

The third choice "0.80m; 431Hz" is correct