To test the resiliency of its bumper during low-speed collisions, a 2 840-kg automobile is driven into a brick wall. The car's bumper behaves like a spring with a force constant 6.00 106 N/m and compresses 3.98 cm as the car is brought to rest. What was the speed of the car before impact, assuming no mechanical energy is transformed or transferred away during impact with the wall

V= 1.82 m/s

Explanation:

Given that

mass , m = 2840 kg

Spring constant ,K = 6 x 10⁶ N/m

Compression in the spring , x = 3.98 cm

Lets take speed of the car before impact = V

Now by using energy conservation

Now by putting the values in the above equation

V= 1.82 m/s

Therefore the speed of the car before impact will be 1.82 m/s.

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue

a.   mass number from atomic number