As a bacterium swims through water it propels itself with its flagella so as to overcome the frictional drag forces and move at, more or less, constant velocity of 100 micrometer/s for periods of time. If the frictional drag force on a bacterium is 0.1 N, how much work does the bacterium do in 1 s?

A) 1 milliJoule

B) 10 microJoule

C) 100 microJoule

D) 1 J

E) 100 milliJoule

B) 10 microJoule

Explanation:

Given

v = 100 micrometer/s

F = 0.1 N

t = 1 s

we get the displacement as follows

d = v*t  ⇒  d = (100 micrometer/s)*(1 s) = 100 micrometer

then we apply the formula

W = F*d*Cos ∅

⇒  W = (0.1 N)*(100 micrometer)*Cos 0°

⇒  W = 10 microJoule

initial speed when it is dropped is 150 ft/s

now at the same moment the acceleration due to gravity is perpendicular to its velocity

so as we know that

now we have centripetal acceleration a = 32 ft/s^2 as its perpendicular to velocity

while tangential acceleration at the same moment will be zero

so

now radius of curvature is given as

so the radius of curvature just after it is dropped is 703.125 ft