Better technology is helping us because we can see more stuff like the microscope we able to make assumptions based on what we saw.
A is the correct answer !!!
The net force on the hanging object is zero. If it were not zero, then the object would be accelerating in some direction.
Answer:

Explanation:
First we have to find the time required for train to travel 60 meters and impact the car, this is an uniform linear motion:

The reaction time of the driver before starting to accelerate was 0.50 seconds. So, remaining time for driver is 1.5 seconds.
Now, we have to calculate the distance traveled for the driver in this 0.5 seconds before he start to accelerate. Again, is an uniform linear motion:

The driver cover 10 meters in this 0.5 seconds. So, the remaining distance to be cover in 1.5 seconds by the driver are 35 meters. We calculate the minimum acceleration required by the car in order to cross the tracks before the train arrive, Since this is an uniformly accelerated motion, we use the following equation:

Answer:
low risk for tissue damage
uses radio waves
the last three are not correct
:)