I am almost 100% positive the answer is A.
Answer:
Speed of physicist car is 0.036c or 1.08 x 10⁷ m/s .
Explanation:
Doppler Effect is defined as the change in frequency or wavelength of the wave as the source or/and observer moving away or towards each other.
In this case, the Doppler effect equation in terms of wavelength is :
......(1)
Here is source wavelength, is observed wavelength, v is speed of the observer and c is the speed of light.
Given :
Source wavelength, = 660 nm = 660 x 10⁻⁹ m
Observed wavelength, = 555 nm = 555 x 10⁻⁹ m
Substitute these values in the equation (1).
v = 1.08 x 10⁷ m/s
<h3><u>Answer;</u></h3>
<em>4. Only some metals are attracted by magnets; these metals are called ferromagnetic.</em>
<h3><u>Explanation;</u></h3>
- <u><em>Magnets are those materials that have the ability of producing magnetic field.</em></u> Magnets attracts materials called magnetic materials and have no effect on non magnetic materials such as wood.
- <em><u>Magnetic materials are materials that are attracted by a magnet, these includes some metal such as iron and steel.</u></em> However some metals are non-magnetic materials, these include, gold, silver, and copper among others,
- Therefore,<em><u> it would be appropriate to say that only some metals are attracted by magnets; these metals are called ferromagnetic.</u></em>