Questions with NEVER
Questions containing absolute negative qualifiers such as NEVER can be tricky. If the question lists statements, it helps to look at each statement and add NEVER just before the verb. For example, rephrase choice A below as “The input force NEVER equals the output force.” Then try to find one example that disproves this statement. The input force and output force can be equal in a lever with the fulcrum in the center. Therefore, the statement is not true. Repeat this process for each choice until you find one that is true in all cases.
Which of the following is NEVER true?
The input force equals the output force.
The ideal mechanical advantage is 1.
The actual mechanical advantage is 1.
The efficiency is 100 percent.
The efficiency is 50 percent.
(Answer: D)
Choose the letter that best answers the question or completes the statement.
An applied force acts upward on a moving wooden crate as shown below. Which of the following statements is TRUE?
The power used to move the crate is 150 W.
The force does no work on the crate.
The force does 150 J of work on the crate.
The force does 66 J of work on the crate.
The force accelerates the crate.
A machine is used to lift boxes in a warehouse. Which change will increase the power of the machine?
decreasing the distance the boxes are lifted
decreasing the force exerted by the machine
increasing the friction inside the machine
decreasing the time it takes to lift the boxes
decreasing the work done by the machine
Which statement is NEVER true for a machine?
The output force is greater than the input force.
The machine changes a force.
The machine changes the direction of a force.
The machine changes the distance over which a force acts.
The work output equals the work input.
Which of the following will increase the actual mechanical advantage of a machine?
decreasing the output force
decreasing the friction
increasing the input force
decreasing the time required
increasing the time required
The diagram below represents a first-class lever. Which point(s) could be the fulcrum for this lever?
A only
B only
C only
A or C only
A, B, or C only
What information is required to calculate the actual mechanical advantage of a lever?
input arm and output arm
input distance and output distance
input force and output force
Work input and work output
internal friction