A pulse with a height of 20 cm and a length of 30 cm travels with a speed of 400 cm/s through a spring that has been stretched so it is 800 cm long. If we want to send another pulse through the spring that will have a different speed, which of the bolded words should we change? List all that will change the speed of the wave.

To send a pulse of different speed, change the tension or stretch on the spring

Explanation:

A pulse is a single disturbance of a particle is a medium. The pulse has an amplitude or and a pulse length in the medium. The speed of the pulse is dependent on the amount of strain or tension ( stretch) applied to the medium. The speed also determines the length of the pulse but is unaffected by the or amplitude of the pulse.  

when earth is in rotational motion around the sun,it displaces from its place.

when a ball is placed on an inclined surface it does both the rotational and circular motion.

explanation:

b.transmitters send radio waves, and receivers capture radio waves.