Unit 4 Review

What is the formula for work?

• W= Fd

• W= f/d

• W= f/t

• W= Ft

Answer explanation

The formula for work (W) is defined as the product of force (F) and distance (d) moved in the direction of the force. Therefore, the correct choice is W= Fd.

Imagine a man lifting a brick repeatedly in the air. How much work does he do with each lift if he lifts it 6.0 m and exerts an average force of 187 N?

• 2211 J

• 1122 J

• 0.03208 J

• 31.17 J

Answer explanation

Work is calculated using the formula: Work = Force x Distance. Here, Work = 187 N x 6.0 m = 1122 J. Therefore, the correct answer is 1122 J.

Tags

NGSS.MS-PS3-4

What is the formula for power?

• P = t/W

• P = Wt

• P = W/t

• P = t/d

Answer explanation

The formula for power (P) is defined as the work done (W) divided by the time (t) taken to do that work. Therefore, the correct formula is P = W/t, which indicates how quickly work is done.

Calculate MA: input force = 6.3 N; output force = 8.6 N

• 0.73

• 54.18

• 14.9

• 1.37

Answer explanation

Mechanical Advantage (MA) is calculated as output force divided by input force. Here, MA = 8.6 N / 6.3 N = 1.37. Thus, the correct answer is 1.37.

What are the six types of simple machines?

• lever, the fulcrum, the wheel and axle, the inclined plane, the wedge, and the screw

• lever, the pulley, the wheel and axle, the inclined plane, the faucet, and the nail

• lever, the fulcrum, the wheel and axle, the inclined plane, the wedge, and the nail

• lever, the pulley, the wheel and axle, the inclined plane, the wedge, and the screw

Answer explanation

The correct answer lists the six types of simple machines: lever, pulley, wheel and axle, inclined plane, wedge, and screw. Other options incorrectly include terms like 'fulcrum' or 'faucet' which are not types of simple machines.

What two simple machines make up a pair of scissors?

• Two levers and a fulcrum

• Two levers and a nail

• Two axles and a wheel

• Two inclined planes and a nail

Answer explanation

Scissors consist of two levers (the blades) that pivot around a fulcrum (the screw or pivot point). This allows them to cut effectively by applying force at the handles to the blades.

Simple machines are divided into two families, what are they?

• Pulley family and Inclined plane family

• Pulley family and Wedge family

• Lever family and Inclined plane family

• Inclined plane family and Wedge family

Answer explanation

Simple machines are categorized into two families: the Lever family and the Inclined plane family. These families encompass various types of simple machines that help in performing work more efficiently.

What is a compound machine?

• A machine that is made up of a fulcrum and pulley.

• A machine that is made up of more than one simple machine.

• A machine that is larger than a simple machine.

• A machine that is made up of a second-class lever connected to a complex pulley.

Answer explanation

A compound machine is defined as a machine that consists of two or more simple machines working together. This distinguishes it from simple machines, which operate independently.

Define Energy:

• How power in a system is measured.

• The total force a system exerts.

• The capacity to do work.

• The ability to convert momentum.

Answer explanation

Energy is defined as the capacity to do work, meaning it is the ability to perform tasks or cause changes in a system. The other options do not accurately capture this fundamental concept.

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5

Define potential energy:

• the energy that an object has because of the position, shape, or condition of the object

• the energy that an object has because of the weight, force, or condition of the object

• the energy that an object has because of the position, force, or condition of the object

• the energy that an object has because of the weight, shape, or speed of the object

Answer explanation

Potential energy is defined as the energy an object possesses due to its position, shape, or condition. The correct choice highlights these aspects, making it the most accurate definition.

Tags

NGSS.MS-PS3-2