WHAT IS THE UNBALANCED FORCE THAT SLOWS DOWN SLIDING DESKS AND MOVING CARS
2 answers:
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Answer:
If she hits the brakes, she will travel 13m before stopping. If she hits the gas, she will travel 28 before the light turns red. She should try to stop
Explanation:
To know how far she will travel before stopping, we need to use a kinematic formula which initial final velocity (Vf), initial velocity (V0), acceleration (a) and distance traveled(x):
The moment in which she stops is when the final velocity equals zero. In this case, initial velocity is 43km/h=12m/s, and its maximum deceleration is -5.4m/s^2. Plugging in these values and solving for x:
She will travel 13m before stopping
If she hits the gas, we need another kinematic formula, which relates distance traveled, initial speed, time (t) and acceleration.
If we know her car can accelerate from 43km/h=12m/s to 70km/h=19m/s in 8.1 s, we can know its acceleration:
In this case, the time before the light turns red is 2.0s. Plugging in all those values:
If she hits the gas, she will travel 28m before the light turns red. She won't even reach the intersection, so she would try to stop.