Multiple Choice
Q. In which of the following is no work done? A. None of the above
Q. A force acting on an object does no work if…. A. There is no force in the object
Q. What is the unit of work? A. Joule
Q. If you exert a 10 N force of 0.9 joules, how much work do you do? A. 9 Joules
Q. If you perform 40 joules of work on 10 N box how high is the shelf when you move it from the floor to the shelf? A. 4 meters tall
Q. The SI unit of power is what? A. Watt
Q. The power of the machine is the what? A. Rate of doing work
Q. If you exert a force of 700 N of 6 meters in 6 seconds, how much watts do you use? A. 700 Watts
Q. Which of the following statements is true? A. To increase power, you can increase the amount of work done in a given time, or you can do a given amount of work in less time.
Q. A 750 Watt motor might be rated as….. A. A 1 horsepower motor
Q. 3730 Watts is how much in horsepower? A. 5
Q. A machine is a device that can multiply what? A. Force
Q. When a machine does work, it cannot do which of the following? A. Increase a force and the distance a force moves an object
Q. How can a machine make work easier? A. By changing the direction of the force
Q. How can you make the work output greater than the work input? A. None of the above
Q. The actual mechanical advantage of a machine…. A. Is less than the ideal mechanical advantage of a machine
Q. If you know the work input and the work output… A. Then you can find the Ideal Mechanical Advantage
Q. If you apply 40 N on a crowbar to lift a rock that weighs 400 N, what is the actual mechanical advantage on the crowbar? A. 10
Q. A 120 meter long ski lift carries people to the second station. What is the ideal mechanical advantage? A. 160
Q. Reducing the friction in a machine…. A. Efficiency
Q. The efficiency is always less than 100% because why? A. Friction
Q. A mechanical advantage requires 420