4.The Dolphin emits short bursts of ultrasound. The echoes of the ultrasound help the dolphins find fish. A SONAR receives a strong echo of ultrasonic signal it sent downwards into the sea 3.6 seconds after the transmission. Calculate the depth of the sea-bed if the speed of ultrasonic waves in sea-water is 1500 m/s.

A0.17kg ball rolls at 0.75m/s to the right on a frictionless surface and collides with a 0.17kg ball rolling to the left at 0.65m/s. (elastic collision) what is the final velocity of the second ball when the first is 0.5m/s to the left? what is the change in kinetic energy before and after?

Three different objects, all with different masses, are initially at rest at the bottom of a set of steps. each step is of uniform height . the mass of each object is a multiple of the base mass : object 1 has mass 4..00m , object 2 has mass 1..96m , and object 3 has mass . when the objects are at the bottom of the steps, define the total gravitational potential energy of the three-object system to be zero. if the objects are then relocated as shown, what is the new total potential energy of the system? each answer requires the numerical coefficient to an algebraic expression. each algebraic expression is given using some combination of the variables , , and , where is the acceleration due to gravity. enter only the numerical coefficient. (example: if the answer is 1..23mgd , just enter 1.23)

Suppose an objects initial velocity is 10m/s and it’s final velocity is 4 m/s. mass is constant. what can best be concluded about the object based in the work-energy theorem