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.
All of the electromagnetic energy radiated from the sun (and from
other stars) is the product of nuclear fusion in its core.
Answer:
She must stop the car before interception, distance traveled 12.66 m
Explanation:
We will take all units to the SI system
Vo = 48Km / h (1000m / 1Km) (1h / 3600s) = 13.33 m / s
V2 = 70 Km / h = 19.44 m / s
We calculate the distance traveled before stopping
X = Vo t + ½ to t²
Time is what it takes traffic light to turn red is t = 2.0 s
X = 13.33 2 + 1.2 (-7) 2²
X = 12.66 m
It stops car before reaching the traffic light turning to red
Let's analyze what happens if you accelerate, let's calculate the acceleration of the vehicle
V2 = Vo + a t2
a = (V2-Vo) / t2
a = (19.44-13.33) /6.6
a = 0.926 m / s2
This is the acceleration to try to pass the interception, now let's calculate the distance it travels in the time the traffic light changes from yellow to red (t = 2.0 s)
X = Vo t + ½ to t²
X = 13.33 2 + ½ 0.926 2²
X = 28.58 m
Since the vehicle was 30 m away, the interception does not happen
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