It is generally a good idea to gain an understanding of the \"size\" of units. C

ID: 1423826 • Letter: I

Question

It is generally a good idea to gain an understanding of the "size" of units. Consider the following objects and calculate their kinetic energy.

A ladybug weighing 28.5 milligrams flies by your head at 3.65 km/h.

A 6.95-kg bowling ball slides (not rolls) down an alley at 23.7 km/h.

A car weighing 1020-kg is moving at a speed of 45.5 km/h.

Based on your results above, which of the following scenarios below likely describe an object possessing one joule of kinetic energy?

1. A mosquito flying through a swamp

2. An elephant running across a field

3. A beetle walking across a jungle floor

4. A tiger running after prey

5. A cat walking down a sidewalk

1) 3.65 kmph = 3.65*5/18 = 1.0138 m/s

KE = 0.5mv^2 = 0.5*28.5*10^-6 * 1.0138^2

KE = 1.46*10^-5 J

2) 23.7 kmph = 23.7*5/18 = 6.583 m/s

KE 0.5*6.95*6.583^2 = 150.6 J

3) 45.5 kmph = 45.5*/18 = 12.64 m/s

KE = 0.5*1020*12.64^2 = 81468 J

based on the above scenario

3) ,5) are likely to have 1 J of KE

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