Answer: The frequency heard will be f = 275.675Hz
Explanation: When an object emitting sound is moving, it occurs a phenomenon called Doppler shift or Doppler effect. What happens is that the sound gets higher when the moving object comes closer the observer and becomes lower after it passes, This change is due to the quantity of waves that passes through an area in an unit of time.
The formula to calculate the Doppler effect is as follows
f = (
) · f₀
f is the observed frequency;
c is the speed of sound;
Vs is velocity of the source;
f₀ is the emitted frequency of source;
Substituting and calculating,
f = 
· 300
f = 275.675 Hz
Thus, the frequency heard by the police officer is 275.675Hz.
Answer:
1. all of them
2. cork and wax
3. iron, lead, and aluminum
4. none of them
Explanation:
1.Which material will displace a volume of water? all of them
When an object is introduced into a container with a volume of water, a volume of liquid equal to the volume of the object is displaced
2.Which material will displace a volume of water less than its own volume?
cork and wax
because the density of the object is less than that of the displaced liquid
3.Which material will displace a volume of water equal to its own volume?
iron, lead, and aluminum
because Arquimedes's principle: any body plunged inside a fluid in this case water experiences an ascending force called push, equivalent to the weight of the fluid removed by the body
4.Which material will displace a volume of water greater than its own volume?
None of them
Answer:
In a positive ion, the number of protons is larger than the number of electrons.
In a negative ion, the number of protons is smaller than the number of electrons.
Explanation:
Each proton carries a positive charge of one unit.
Each elec in tron carries a negative charge of one unit.
In an atom, there are as many protons as electrons. Hence, they are neutral.
However, in a positive ion, there are less negative charge than positive charge. Hence the net charge is positive. That also means that there are fewer negatively-charged electrons than positively-charged protons.
Similarly, in a negative ion, there are more negative charge than positive charge. Hence the net charge is negative. That also means that there are more negatively-charged electrons than positively-charged protons.
