I think the correct answer from the choices listed above is option D. The difference between a chemical change and a physical change is lies in the fact that a physical change does not break any bonds while a chemical change does form new substances. Hope this answers the question.
Answer:
120 J
Explanation:
Formula Of Work= Work= Force x Displacement
Work= 20 N x 6.0
Work= 120 Joules
The reason I put joules because the Unit of work is joules
Answer:
a. -5,4
b. 28
Explanation:
(see how to solve in pic)
Answer:
-3.396 m/s or 3.465 m/s
Explanation:
v = Speed of sound in air = 343 m/s
= Relative speed of the singer
f = Observed frequency
f' = Actual frequency
1% change can mean 
From the Doppler effect equation we have
The velocity is -3.396 m/s
when 
The velocity is 3.465 m/s
The instrument is a Geiger counter and is used to measure radioactive level around people's bodies.
