Answer:
C. a rolling bowling ball
I just answered this question on my quiz.
Given: The number = 0.0069 that has to be expressed in scientific notation
Concept: When we express any number in scientific notation then we shall consider two points.
(i) If we shift the decimal point from left to right after first (non-zero) digit then we count the number of shifted place of decimal and write them in terms of the negative power of 10. For example, 0.004789 = 4.789 ×10⁻³
(ii) If we shift the decimal point from right to left after first (non-zero) digit from the left end then we count the number of shifted place and write then in terms of the positive power of 10. For example, 4789.24 = 4.78924 ×10⁺³ = 4.78924 ×10³ Now, we shall convert the given number 0.0069 in scientific notation
0.0069 = 6.9 ×10⁻³ because we have shifted the decimal from left to right for three places that is after digit 6.
Hence, the last option 6.9 ×10⁻³ will be the correct option.
D. physical property
the bonds between molecules of mercury are breaking so it's physical and it's not changing the chemical composition of the substance
Answer:
Final momentum after a head on collision is -2kgm/s
Explanation:
One ball moves to the right and the other moves opposite and momentum is a vector quantity so that considering the direction
Initial momenta are P₁=2x3=6kgm/s P₂=4x(-2)=-8kgm/s
Final momentum is the vector sum of P(final)= 6-8= -2 kgm/s
