A bicyclist travels the first 1600 m of a trip at an average speed of 8 m/s, travels the next 1200 m in 90 s and spends the last 50 s at a speed of 15 m/s. Find the average speed of the bicyclist for this trip.

Acave rescue team lifts an injured spelunker directly upward and out of a sinkhole by means of a motor-driven cable. the lift is performed in three stages, each requiring a vertical distance of 11.0 m: (a) the initially stationary spelunker is accelerated to a speed of 4.80 m/s; (b) he is then lifted at the constant speed of 4.80 m/s; (c) finally he is decelerated to zero speed. how much work is done on the 78.0 kg rescue by the force lifting him during each stage

What is the energy of a photon of ultraviolet radiation with a frequency of 4.4 × 1015 hz? planck’s constant is 6.63 × 10–34

If a simple machine reduces the strength of a force, what must be increased?