A. Advanced new safety features that get everyone home at night.
Explanation:
The triple beam balance is used to measure masses very precisely; the reading error is 0.05g
The average power is 
Explanation:
First of all, we calculate the work done to accelerate the car; according to the work-energy theorem, the work done is equal to the change in kinetic energy of the car:
where
:
is the final kinetic energy of the car, with
m = 2000 kg is the mass of the car
v = 60 m/s is the final speed of the car
is the initial kinetic energy of the car, with
u = 30 m/s is initial speed of the car
Soolving:
Now we can find the power required for the acceleration, which is given by

where
t = 9 s is the time elapsed
Solving:

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Answer:
21/5 seconds or 4.2 seconds
Explanation:
Distance=Speed*Time
21=5 *Time
21/5=Time
4.2=time
I racked my brain for almost 10 minutes, until suddenly,
it hit me !
You're breathing one right now ! So am I .
Air is a mixture of a lot of elements.
Nitrogen, Oxygen, and Argon account for 99.964 percent.
The other 0.036 percent is mainly Neon, Helium, Krypton,
and Hydrogen ... more elements.
Then there are Carbon Dioxide and water vapor.
Yes, those are compounds. But together, they add up
to very little of the air we breathe, and if both of them
suddenly disappeared, we would hardly notice it.