PS TB 04.1 Work and Machines

Which of the following best describes how machines change work?

• They increase the amount of work needed.

• They make work easier by increasing force.

• They decrease the efficiency of work.

• They have no effect on work.

Answer explanation

Machines make work easier by allowing us to apply greater force with less effort, enabling us to lift heavier objects or perform tasks more efficiently.

Tags

NGSS.HS-PS2-1

Machines are used to make work easier by ______.

• increasing the distance

• decreasing the force

• increasing the force

• decreasing the distance

Answer explanation

Machines make work easier by increasing the force applied to an object, allowing us to lift or move heavier loads with less effort. This is why 'increasing the force' is the correct answer.

Tags

NGSS.MS-PS2-2

What is the term for the ability of a machine to convert input work into output work without any loss?

• Work

• Efficiency

• Mechanical Advantage

• Simple Machine

Answer explanation

Efficiency refers to the ability of a machine to convert input work into output work with minimal or no loss. It measures how effectively a machine uses energy, making it the correct term for this concept.

Tags

NGSS.HS-PS3-3

A _______ is a device that makes work easier by changing the size or direction of a force.

• Work

• Machine

• Efficiency

• Mechanical Advantage

Answer explanation

A machine is a device that helps perform work by altering the size or direction of a force, making tasks easier. This definition aligns with the term 'machine', distinguishing it from other options like work or efficiency.

What is the definition of force?

• A type of energy

• A push or pull exerted on an object

• A form of matter

• A chemical reaction.

Answer explanation

Force is defined as a push or pull exerted on an object, which is the correct choice. It is not a type of energy, a form of matter, or a chemical reaction.

What is a machine?

• A) A device that makes work harder

• B) A device that makes work easier

• C) A device that does not affect work

• D) A device that only changes the direction of force.

Answer explanation

A machine is designed to make work easier by reducing the effort needed to perform tasks. Therefore, the correct answer is B) A device that makes work easier.

A machine can change the size of a force, the direction of the force, or the ______ over which a force acts.

• speed

• distance

• color

• temperature

Answer explanation

A machine can change the size, direction, or distance over which a force acts. 'Distance' is the correct choice as it refers to the range over which the force is applied, unlike speed, color, or temperature.

What is a machine?

• A) A device that changes force or increases motion from work

• B) A tool that only cuts materials

• C) A vehicle for transportation

• D) A type of computer.

Answer explanation

A machine is defined as a device that changes force or increases motion from work, making option A the correct choice. Options B, C, and D are too narrow and do not encompass the broader definition of a machine.

A simple machine is a machine that does work with only one movement of the machine. Which of the following is NOT a type of simple machine?

• Lever

• Pulley

• Engine

• Wedge

Answer explanation

An engine is a complex machine that requires multiple movements to operate, unlike simple machines such as levers, pulleys, and wedges, which perform work with a single movement.

A compound machine is a combination of two or more simple machines. For example, a pair of scissors is a compound machine. It combines two wedges and two ____.

• Levers

• Pulleys

• Wheels

• Screws

Answer explanation

A pair of scissors consists of two wedges (the blades) and two levers (the handles). The levers allow the user to apply force to cut, making 'levers' the correct answer.