RECF Mechanical

To raise the arm of a robot, the last of 4 spur gears in a simple gear train must rotate clockwise. in what direction does the input (first) gear turn?

• Clockwise

• Counterclockwise

A robot has wheels with 4-inch diameter. each wheel rolls 5 revolutions on a horizontal surface without slipping. how far did the robot travel?

• 26.8 inches

• 62.8 inches

• 82.6 inches

• 68.2 inches

Which of the following statements is equivalent of the first law of thermodynamics?

• In all energy exchanges, if no energy enters or leaves the system, the potential energy of the state will always be less than that of the initial state

• The entropy of a perfect crystal of a pure substance approaches zero as the temperature approaches zero.

• Energy cannot be created or destroyed

One hot day matt's air conditioner broke. He thought of an idea to cool his house by opening his refrigerator. Three hours later his house temperature went up by two degrees. Why did this happen?

• The condenser on the refrigerator ran constantly

• The ac started working again

• The fridge broke

Two children are playing on a see-saw. The one on the left weighs 80 lbs. and the one on the right weighs 100 lbs. If the child on the left is 3 feet from the pivot, how far must the child from the right be for the see-saw to be balanced?

• 2.4 ft

• 4.2 ft

• 3.6 ft

• 6.3 ft

Which of the following types of gears would be found in a parallel shaft gear train?

• Gear Rack

• Worm Gear

• Screw Gear

• Spur Gear

What type of simple machine is in the nutcracker pictured?

• Screw

• Wheel and axle

• Lever

• Inclined plane

A 12-tooth sprocket and a 36-tooth sprocket are connected by a chain. If the 12-tooth sprocket is rotating clockwise, in what direction is the 36-tooth sprocket turning?

• Counterclockwise

• Clockwise

Suppose an automobile travels 5 miles in 20 minutes. What is the average speed of the car in miles per hour?

• 15 mph

• 10 mph

• 5mph

• 20mph

If a robot had 5-inch wheels that were spinning at 120 RPM, how fast would the robot be moving?

• 41.3 in/s

• 13.4 in/s

• 31.4 in/s

• 43.1 in/s

• 14.3 in/s