Maya builds a device with a hand crank, a small motor, and a bulb in a circuit. When she cranks faster, the bulb glows brighter. What energy change is happening?

Design A uses one battery and a small buzzer. Design B uses several batteries and a louder horn. Both can be heard across the room, but the rules allow only one battery. Why is Design B rejected?

Ana wants to know whether a thicker rubber band makes her wind-up toy car travel faster. To run a fair test, what should she do?

A team builds a device that uses light to turn a small fan. Under a dim lamp the fan turns slowly, and under a bright lamp it turns quickly. What does this evidence show?

A student builds a device with a wound-up rubber band that launches a foam dart. When she winds the rubber band more times before releasing it, the dart flies farther. What does this evidence show about the device?

A wind-powered device has blades connected to a small generator that lights an LED bulb. What is the correct order of energy conversion in this device?

A team's hand-crank flashlight glows only dimly, even when they crank quickly. They want it to glow brighter without adding more people to crank it. What redesign is most likely to help?

While Leo's motor device runs, he notices that the wires feel warm. What is the best explanation?

True or False: A buzzer wired to a battery converts energy from one form into another form.

A group's cardboard windmill device lifts a paper clip only partway up. What is the best next step for these young engineers?

Priya's device uses a small motor to tap a toy drum, making a tapping sound. What is the correct order of energy conversion in this device?

Before building, a class agrees that its energy-converting device must cost less than a set amount of money. In engineering design, this money limit is called a ___.

A student builds a simple flashlight using a battery, wires, and a bulb. What energy conversion happens when the flashlight is turned on?

Which device is designed mainly to convert light energy from the Sun into thermal energy?

A student turns the handle of a hand-crank generator to light a small bulb. When she stops turning, the bulb goes dark right away. What does this show?

True or False: A device that converts energy creates new energy from nothing.

A team wants to improve a solar oven so it heats water faster. Which design change would most likely help?

Two teams test their rubber band cars three times each. Car A goes 2 m, 3 m, and 2 m. Car B goes 4 m, 5 m, and 4 m. Which conclusion do the results best support?

A rubber band car moves forward after the wound rubber band is released. Which energy conversion best describes this?

Ravi's team spends three days building and testing their solar oven, but the challenge rules allow only two days. On judging day, their oven heats water well. Why might the judges still say the team did not meet the challenge?