Which of the following statements are IMPOSSIBLE? Choose all that apply A. A car

Question

Which of the following statements are IMPOSSIBLE? Choose all that apply A. A car drovedown the highway with a speed of -78 mph B. A trucktraveled a distance of 124 mi. C. A rock was thrownstraight up into the air. At the peak, its speed was 9.8m/s. D. 1 m = 100mm E. An object moveda total distance of 14 m and had a total displacement of 0m. Which of the following statements are IMPOSSIBLE? Choose all that apply A. A car drovedown the highway with a speed of -78 mph B. A trucktraveled a distance of 124 mi. C. A rock was thrownstraight up into the air. At the peak, its speed was 9.8m/s. D. 1 m = 100mm E. An object moveda total distance of 14 m and had a total displacement of 0m. C. A rock was thrownstraight up into the air. At the peak, its speed was 9.8m/s. D. 1 m = 100mm E. An object moveda total distance of 14 m and had a total displacement of 0m.

Explanation / Answer

Impossible:
A,C,D A) Speed can never be negative. Speed is defined as themagnitude of a velocity, and a magnitude, by definition, is apositive quantity (a scalar in fact, with no direction). Velocity, however, can be negative since it is given direction(example, a relative velocity can be negative relative to someother referrence point). C) A rock is thrown up into the air. The reason the rockfalls is because its potential energy is increasing, hence itskinetic energy is being converted to potential energy, and when thekinetic energy is zero, potential energy is max--this is when therock is at its peak, when its KE = 0, and KE = (1/2)mv2 therefor v = 0, so a projectile will always be atinstantaneous rest (v=0) at its peak altitude. Another reason to explain why gravity "pulls things down" isthat there is an associated potential energy due to gravity: U = mgh As h increases, U increases, i.e. as an object moves higherand higher, it gains more potential energy U. Objects with stored potential energy tend to release theirenergy, hence fall. D) 1 m = 101 dm = 102 cm =103 mm = 106 m = 109 nm =1012 pm = 1015 fm ---------------------------------------------- B and E are possible because:
B) v = dx/dt = displacement/time = space/time assuming the truck can move, it can travel space in a timeperiod, space = distance Therefor a truck can travel a distance as long as a truck canmove in time (which they can) E) Consider a circle of circumference 14m. Although anobject travels a circular distance of 14m, its net displacement =0 therefor v = 0, so a projectile will always be atinstantaneous rest (v=0) at its peak altitude. Another reason to explain why gravity "pulls things down" isthat there is an associated potential energy due to gravity: U = mgh As h increases, U increases, i.e. as an object moves higherand higher, it gains more potential energy U. Objects with stored potential energy tend to release theirenergy, hence fall. D) 1 m = 101 dm = 102 cm =103 mm = 106 m = 109 nm =1012 pm = 1015 fm ---------------------------------------------- B and E are possible because:
B) v = dx/dt = displacement/time = space/time assuming the truck can move, it can travel space in a timeperiod, space = distance Therefor a truck can travel a distance as long as a truck canmove in time (which they can) E) Consider a circle of circumference 14m. Although anobject travels a circular distance of 14m, its net displacement =0

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