Question

Paul and Ivan are riding a tandem bike together they're moving at a speed of 5 meters per second Paul and Ivan each have a mass of 50 kg what can I do to increase the bikes kinetic energy.

a: he can let Ivan off at the next stop

b: he can pedal harder to increase the speed to 10 meters per second

c: he could reduce the speed to 3 meters per second

d: he can pick up a third Rider ​

Answer 1

Recall the equation for Kinetic Energy: = m

Knowing this, we know that there are only two factors that can alter Kinetic Energy: mass and velocity. Looking at the equation, we can deduce that an increase in either mass or velocity would increase the overall Kinetic Energy as long as everything else stays constant.

a) He can let Ivan off at the next stop - Wrong. By letting Ivan off, mass decreases. Assuming Paul maintains the same speed as before, Kinetic Energy decreases.

b) He can pedal harder to increase the speed to 10 meters per second - Correct. By speeding up, "v" increases and the overall Kinetic Energy increases.

c) He could reduce the speed to 3 meters per second - Wrong. Looking at the equation, we know reducing speed would reduce Kinetic Energy

d) He can pick up a third rider - Correct, assuming they keep the same speed after picking up the third rider: if mass increases and velocity stays the same, then Kinetic Energy will increase.

Answers - B, D

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