(Hurry please) A student drops a rubber ball onto a surface. Assume that this is a closed system. The ball bounces, but each
successive bounce is shorter than the one before it.
Eventually, the ball comes to a stop.
Which statement provides evidence that supports the idea that energy is
conserved in this closed system?
A. The ball bounces many times, suggesting the energy is used up
efficiently
O B. The ball makes a sound with each bounce, suggesting that some
kinetic energy transformed into sound.
O C. The ball needs a push or pull to start moving, suggesting it needs
a constant input of energy.
OD. The ball moves through air, suggesting that the ball has
mechanical energy

In a wind tunnel the speed changes as the cross sectional area of the tunnel changes. if the speed in a 6' x 6' square test section is 100 mph, what was the speed upstream of the test section where the tunnel measured 20' x 20'? use conservation of mass and assume incompressible flow. conservation of mass requires that as the flow moves through a path or a duct the product of the density, velocity and cross sectional area must remain constant; i.e., that ova-constant. a model is being tested in a wind tunnel at a speed of 100 mph if the flow in the test section is at sea level standard conditions, what is the pressure at the model's stagnation point? (a) the tunnel speed is being measured by a pitot-static tube connected to a u- tube manometer. what is the reading on that manometer in inches of water? (b) at one point on the model a pressure of 2058 psf is measured. what is the local airspeed at that point?

Within a pendulum, as potential energy decreases, energy increases. a. heat b. kinetic c. frictional d. gravitational

For waves in the ocean, the medium of the waves is a. air b. water c. energy d. a passing boat