multipal choice question on mechanics

a machine is supplied energy at a rate of 4,000 W and does useful work at a rate of 3,760 W. what is the efficiency of the machine? a. 92 percent b. 94 percent c. 96 percent d. 97 percent?

Radius of a Curve

A car with a mass of 1,200 kilograms is moving around a circular curve at a uniform velocity of 20 meters per second, the centripetal force on the car is 6,000 newtons. What is radius of the curve? a. 160 meters b. 80 meters c. 32 meters or d. 16 meters?

question on machanics

what force is required to accelerate a body with a mass of 15 kilograms at a rate 8/S2 ( the 2 is small obove the s) aswers a. 1.875 kg b. 23 kg c. 23N or d. 120N?

Beam deflection and Stress at centroid?

Sometimes the term centroid throws me for a loop. So, how would I set this problem up? I'm asked to determine the deflection of the tip of a beam and max direct stress and location for a 2000N load. Given load=2000N, on the tip of a 1m beam. Beam dimensions are H=80mm B=W=40mm and t=thickness of 1.5mm.

Beam deflection at corner through centroid?

Sometimes the term centroid throws me for a loop. So, how would I set this problem up? I'm asked to determine the deflection of the tip of a beam for a 2000N load. The section is rotated 15 degrees. The load application point is through the centroid of section. Another way to describe the picture is that the beam is cocked to one side by 15 degrees and the load almost at one corner [maybe width*cos(15)] aiming to the diagonal corner. Given load=2000N, on the tip of a 1m beam. Beam dimensions are H=80mm B=W=40mm and t=thickness of 1.5mm.