A. If a cyclist of mass 70kg uses a bicycle of mass 7kg, how much work must the cyclist do against gravity in order to ascend to 2100m from sea level. b. One particular descent goes from 2100m to 1600m. Assuming the work done against friction is 90% of the potential energy change of the cyclist and cycle, what Increase in speed in km/h can a rider attain by the end of the descent?

c. What is the average rate of energy conservation of the cyclist and cycle if the descent in part 'b' takes 1 minute at constant speed.

(Acceleration due to gravity, g = 10ms^-2)

the diagram which shows forces as either balanced = same speed or unbalanced = accelerarting

no. dot product   =0 when vecs at right angles

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me