Julian rides his bike uphill for 45 minutes, then turns around and rides back downhill. it takes him 15 minutes to get back to where he started. his uphill speed is 3 miles per hour slower than his downhill speed. find julian’s uphill and downhill speed.

1.5mi/hr, 4.5mi/hr

Explanation:

Given:

45 min = 0.75h, 15 min = 0.25h

(1) 0.75v₁ = 0.25v₂

(2) v₁ = v₂ - 3

Solve for v₁ and v₂:

0.75(v₂ - 3) = 0.25v₂ = 0.75v₂ - 2.25 = 0.25v₂

0.5v₂ = 2.25

v₂ = 4.5

v₁ = 1.5

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.