Physical Science Question Please Help!!?
1. A car traveling 20 mph can stop in about 40 ft is the same car was traveling twice as fast, its stopping distance would be roughly:
A.) 160 ft
B.) 80 ft
C.) 40 ft
D.) 60 ft
2. Energy sources used today are mostly in what form of energy
A.) electrical
B.) radiant
C.) nuclear
D.) chemical
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1) If we assume that the force decelerate the car remains the same even at different speeds, we have
Kinetic energy of the car = distance_to_decelerate_to_zero * force_to_decelerate
Because kinetic energy = 1/2*Mass*Velocity^2, the kinetic energy will be 4 times if the velocity is only 2 times, thus the distance needed to decelerate will be 4 times.
Answer B)80
2) I think it's D) chemical energy because the main energy sources are all fossil fuels, like coal and oil and natural gases. The process to burn them is the process to release the energy stored in their original chemical forms and transform them into another chemical forms.
Lavalamp: Correct reasoning but I think you meant to say 160 ft.
Question 2 isn't really well formed. You could argue that d) is the right answer b/c you are releasing the energy in the chemical bonds when chemical transformations occur. You could argue b) b/c you're using that chemical energy to make heat and therefore do work to generate electricity. You could say a) as most of the energy "created" ultimately ends in the form of moving electrons. So... unless question 2 is better phrased it's ambiguous enough to not really have a single correct answer.
1. B) 80 feet (twice the speed, four times the kinetic energy, so four times the stopping distance)
2. 1) chemical (oil, coal, natural gas - fossil fuels in general)