In a crash test the strapped-in, 75-kg dummy moves a distance of 0.80 m when the test car is slammed straight into a wall at 11.2 m/s (~25 mph). the average force acting on the dummy during the collision is how many times his own weight?

Explanation:

It is given that,

Mass of the dummy, m = 75 kg

Distance, d = 0.8 m

Initial speed of the dummy, u = 0

Final speed of the dummy, v = 11.2 m/s

Firstly finding the acceleration of the test car. Using third equation of motion to find it as :

Let F is the average force. It is given by the product of mass and acceleration. It is given by :

F = 5880 N

Taking ratios,

The average force acting on the dummy during the collision is 8 times of his weight. Hence, this is the required solution.

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)