Energy Unit Part One

At which position is the potential energy the greatest?

• Position 1

• Position 2

• Position 3

• Position 4

Answer explanation

Potential energy increases as the object is higher above the earth's surface. The higher the object is, the greater the (gravitational) potential energy.

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NGSS.MS-PS3-2

At which position is the kinetic energy of the object the greatest?

• Position 1

• Position 2

• Position 3

• Position 4

Answer explanation

As the pendulum swings, the potential energy is converted into kinetic energy. As the object trends upwards, it begins to gain potential energy. Therefore, the point at which the kinetic energy is the greatest, is the exact point in which the object is about to swing upwards.

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NGSS.MS-PS3-1

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A bicycle rider is traveling up a hill. When the rider reaches the top of the hill, she stops to rest. Then she travels down the hill. The diagram shows the rider in the three different positions.

​Which of these correctly describes the potential energy and the kinetic energy of the bicycle rider?

• When the rider is at the top of the hill, the potential energy is greatest and the kinetic energy is least.

• As the rider moves up the hill, the kinetic energy increases and the potential energy decreases

• When the rider goes down the hill, the potential energy increases while the kinetic energy decreases.

• As the rider reaches the bottom of the hill, both her kinetic and potential energy decrease

Answer explanation

As an object increase in height, they increase their potential energy. As the potential energy increases in an object, the kinetic energy decreases.

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Several objects are located on a set of shelves in a classroom. The mass of each object is given in the table, and the diagram shows the location of each object on the set of shelves.

​​Which object has the largest potential energy relative to the floor?

• bowl

• lunchbox

• rubber ball

• school supply box

Answer explanation

Both the school supply box and the bowl are at the same position above the earth's surface, so we have to look at the mass of each object. Because the school supply box has a greater mass, then it has the greatest potential energy. We know this, as the potential energy equation states that PE= MASS X Gravity x Height. Both the height and gravity are the same for both the bowl and school supply box, the only difference is the mass. By increasing the mass, you also increase the potential energy.

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NGSS.MS-PS3-2

​Which of these best describes the energy transformations that will occur when the battery is attached to this circuit?

• chemical-electrical-mechanical

• electrical-chemical-mechanical

• chemical-heat-electrical

• electrical-chemical-heat

Answer explanation

The battery is the energy source of this system (chemical). The wires transform that energy into electrical energy, in which powers the fan. As the fan blades spin, it generates mechanical energy.

Chemical energy is stored energy in the bonds of elements

Electrical energy is the movement of electrons

Mechanical energy is energy in motion

What is the sequence of the energy transformations represented in the diagram?

• mechanical-chemical-solar

• solar-electrical-mechanical

• mechanical-electrical-solar

• solar-chemical-electrical

Answer explanation

The source of energy for this system comes from the sun (solar). Solar energy is then transformed into electrical energy from the motor, which is then transformed into mechanical energy as the car begins to move.

A battery powers an alarm in a toy. Which is an energy transformation that takes place in this device?

• electrical- sound- kinetic

• kinetic- sound- chemical

• chemical- electrical- sound

• sound- chemical- electrical

Answer explanation

The battery of the toy (chemical) is transformed into electricity (electrical) that is used to power the alarm (sound)

​Which best describes the energy transformation that moves the Ferris wheel?

• solar-electrical-mechanical

• mechanical- electrical- potential

• solar- mechanical- chemical

• potential- electrical - chemical

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NGSS.MS-PS3-4

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A bowling ball, baseball, golf ball, and ping pong ball are all rolling down a bowling lane at the same speed. Which one has the most kinetic energy? 

• Bowling Ball

• Baseball

• Golf Ball

• Ping Pong Ball

Answer explanation

The object with the most mass is going to have the greatest kinetic energy. We know that the equation for kinetic energy states that KE= 1/2 MASS x Velocity^2. If you increase the mass, you also increase the kinetic energy.

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As the mallet falls, energy is transformed from...

• Kinetic energy to potential energy

• elastic energy to mechanical energy

• potential energy to kinetic energy

• gravitational energy to chemical energy

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