9.during an experiment that paul and dawn performed, the stretch of a spring was directly proportional to the force applied to the spring. when they put the data on a graph, they would expect to have what type of curve?

Explanation:

The spring force is: F = kx

The stretch of the spring is directly proportional to the force applied on the spring.

Here, k is the spring constant.

when data on the graph would be plotted: stretch of the spring versus force on the spring, a straight line would be observed.

This is due to echo, because in empty room there is continuous reflection of sound waves occur but in furnished room there are many sound absorbing materials therefore echo do not occur.