Is there any difference between reflection and echo???

Lets say that an object of a certain volume has a certin mass. what happens to its mass when you double its volume?

Adelivery truck leaves a warehouse and travels 2.60 km north. the truck makes a left turn and travels 1.25 km west before making another right turn to travel 1.40 km north to arrive at its destination. what is the magnitude and direction of the truck's displacement from the warehouse?

Astone is dropped with no initial velocity from the top of a cliff and hits the ground a time of 3.9 s later. what is the height of the cliff, in units of meters? you may assume that air resistance is negligible. give the answer as a positive number question 15 a figure skater is rotating at a rate of 200 revolutions per minute. what is the angular speed, in units of rad/s? 200 o 20.9 12000 o 3.33