Starting from home, you bicycle 25 km north in 2.4 h and then turn around and pedal straight home in 1.4 h . what are your (a) displacement at the end of the first 2.4 h , (b) average velocity over the first 2.4 h , (c) average velocity for the homeward leg of the trip, (d) displacement for the entire trip, and (e) average velocity for the entire trip

Part a)

Part b)

Part c)

Part d)

Displacement for entire trip = 0

Part e)

Average velocity for entire trip will be zero

Explanation:

Part a)

Displacement after t = 2.4 hours is the straight line distance between initial and final positions

so we have

Part b)

Average velocity is defined as

Part c)

During his return journey the displacement will be same

so average velocity is defined as

Part d)

Displacement for entire trip = 0

as initial and final position will be same

Part e)

Average velocity for entire trip will be zero

Work cannot be increased by using a machine of some kind.

A machine is any device in which the effort applied at one end overcomes a load at the other end.

Machines are generally used to perform different tasks faster.

However, a simple machine can not be used to increase the amount of work done at any time.

Force, speed and torque can all be increased using machines.

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