Question

choose the best answers.
7.1) __ a __ is a combination of simple machines.
a. screw
b. compound machine
c. wedge
7.2) which two are benefits of using compound machines?
□ they make work easier.
□ they make work more careful.
□ they make work possible.
□ they make work more complex.
7.3) which four are examples of compound machines?
□ a bicycle
□ a ramp
□ a crane
□ a pair of scissors
□ a screw
□ a wheelbarrow
answer the question.
7.4) what does it mean to be efficient? ____

Explanation:

7.1: A compound machine is defined as a combination of two or more simple machines, while screw and wedge are simple machines.
7.2: Compound machines reduce the force needed for work, making it easier, and enable tasks that would be impossible with simple machines alone. The other options are incorrect as they do not describe benefits.
7.3: A bicycle uses gears, wheels/axles; a crane uses pulleys and levers; scissors use levers and wedges; a wheelbarrow uses levers and wheels/axles. Ramp and screw are simple machines.
7.4: Efficiency in machines refers to maximizing output work while minimizing wasted energy/input work.

Answer:

7.1) B. compound machine
7.2)

• They make work easier.
• They make work possible.

7.3)

• a bicycle
• a crane
• a pair of scissors
• a wheelbarrow

7.4) Being efficient means accomplishing a task (or doing work) with the least amount of wasted energy, effort, or resources; for machines, it is the ratio of useful output work to total input work, where higher efficiency means less energy is lost to factors like friction.