farmer bob decides to use a compound pulley to raise a box up to the top of his barn.

what is the purpose of using a simple machine in this case?

a) to reduce the amount of friction
b) to reduce the distance the box has to travel
c) to reduce the amount of work needed to lift the box
d) to reduce the amount of force needed to lift the box

Aforce of 240.0 n causes an object to accelerate at 3.2 m/s2. what is the mass of the object?

Look at the potential energy diagram for a chemical reaction. which statement correctly describes the energy changes that occur in the forward reaction?

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?