Evidence of Energy Change - Middle School Physical Science
Card 1 of 25
A $1\ \text{kg}$ cart speeds up from $2\ \text{m/s}$ to $4\ \text{m/s}$. By what factor does $KE$ change?
A $1\ \text{kg}$ cart speeds up from $2\ \text{m/s}$ to $4\ \text{m/s}$. By what factor does $KE$ change?
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It increases by a factor of $4$. Initial $KE=2\ \text{J}$, final $KE=8\ \text{J}$, so factor is $4$.
It increases by a factor of $4$. Initial $KE=2\ \text{J}$, final $KE=8\ \text{J}$, so factor is $4$.
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What is the kinetic energy of a $4\ \text{kg}$ object moving at $2\ \text{m/s}$?
What is the kinetic energy of a $4\ \text{kg}$ object moving at $2\ \text{m/s}$?
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$8\ \text{J}$. Using $KE=\frac{1}{2}(4)(2^2)=\frac{1}{2}(4)(4)=8\ \text{J}$.
$8\ \text{J}$. Using $KE=\frac{1}{2}(4)(2^2)=\frac{1}{2}(4)(4)=8\ \text{J}$.
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What is the kinetic energy of a $2\ \text{kg}$ object moving at $3\ \text{m/s}$?
What is the kinetic energy of a $2\ \text{kg}$ object moving at $3\ \text{m/s}$?
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$9\ \text{J}$. Using $KE=\frac{1}{2}(2)(3^2)=\frac{1}{2}(2)(9)=9\ \text{J}$.
$9\ \text{J}$. Using $KE=\frac{1}{2}(2)(3^2)=\frac{1}{2}(2)(9)=9\ \text{J}$.
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Which change in speed shows a decrease in kinetic energy if mass stays constant?
Which change in speed shows a decrease in kinetic energy if mass stays constant?
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Speed decreases. Lower speed means less kinetic energy when mass is constant.
Speed decreases. Lower speed means less kinetic energy when mass is constant.
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Which observation is evidence that kinetic energy changed into thermal energy during an interaction?
Which observation is evidence that kinetic energy changed into thermal energy during an interaction?
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Temperature increases. Heat generation shows kinetic energy converted to thermal energy.
Temperature increases. Heat generation shows kinetic energy converted to thermal energy.
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Which change in speed shows an increase in kinetic energy if mass stays constant?
Which change in speed shows an increase in kinetic energy if mass stays constant?
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Speed increases. Higher speed means more kinetic energy when mass is constant.
Speed increases. Higher speed means more kinetic energy when mass is constant.
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Which observation is evidence that kinetic energy changed into sound energy during an interaction?
Which observation is evidence that kinetic energy changed into sound energy during an interaction?
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A sound is produced. Sound production shows kinetic energy converted to sound waves.
A sound is produced. Sound production shows kinetic energy converted to sound waves.
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What is kinetic energy in terms of mass and speed?
What is kinetic energy in terms of mass and speed?
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$KE=\frac{1}{2}mv^2$. Energy of motion depends on mass and speed squared.
$KE=\frac{1}{2}mv^2$. Energy of motion depends on mass and speed squared.
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What happens to kinetic energy when speed is cut in half and mass stays the same?
What happens to kinetic energy when speed is cut in half and mass stays the same?
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It becomes $\frac{1}{4}$ as large. KE depends on speed squared, so halving speed gives one-fourth energy.
It becomes $\frac{1}{4}$ as large. KE depends on speed squared, so halving speed gives one-fourth energy.
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What happens to kinetic energy when mass doubles and speed stays the same?
What happens to kinetic energy when mass doubles and speed stays the same?
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It doubles. KE is directly proportional to mass when speed is constant.
It doubles. KE is directly proportional to mass when speed is constant.
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Which observation is evidence that kinetic energy changed into deformation energy during an interaction?
Which observation is evidence that kinetic energy changed into deformation energy during an interaction?
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An object bends, dents, or stretches. Shape changes show kinetic energy went into deforming the material.
An object bends, dents, or stretches. Shape changes show kinetic energy went into deforming the material.
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A moving ball hits a wall and stops. Identify the best evidence that its kinetic energy decreased.
A moving ball hits a wall and stops. Identify the best evidence that its kinetic energy decreased.
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Its speed becomes $0\ \text{m/s}$. Zero speed means all kinetic energy was lost in the collision.
Its speed becomes $0\ \text{m/s}$. Zero speed means all kinetic energy was lost in the collision.
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Identify the evidence of increased kinetic energy in a collision when a cart leaves faster.
Identify the evidence of increased kinetic energy in a collision when a cart leaves faster.
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Higher speed after the interaction. Greater speed means more kinetic energy after the collision.
Higher speed after the interaction. Greater speed means more kinetic energy after the collision.
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Identify the evidence of decreased kinetic energy when two objects stick together after colliding.
Identify the evidence of decreased kinetic energy when two objects stick together after colliding.
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Lower speed of the combined object. Combined objects move slower, showing kinetic energy was lost.
Lower speed of the combined object. Combined objects move slower, showing kinetic energy was lost.
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Which object has greater kinetic energy: $m=1\ \text{kg}, v=6\ \text{m/s}$ or $m=2\ \text{kg}, v=4\ \text{m/s}$?
Which object has greater kinetic energy: $m=1\ \text{kg}, v=6\ \text{m/s}$ or $m=2\ \text{kg}, v=4\ \text{m/s}$?
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$m=1\ \text{kg}, v=6\ \text{m/s}$. First has $KE=18\ \text{J}$, second has $KE=16\ \text{J}$.
$m=1\ \text{kg}, v=6\ \text{m/s}$. First has $KE=18\ \text{J}$, second has $KE=16\ \text{J}$.
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Which observation is evidence that kinetic energy changed into light energy during an interaction?
Which observation is evidence that kinetic energy changed into light energy during an interaction?
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Light is produced (spark or glow). Light emission shows kinetic energy converted to electromagnetic energy.
Light is produced (spark or glow). Light emission shows kinetic energy converted to electromagnetic energy.
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A $3\ \text{kg}$ cart slows from $6\ \text{m/s}$ to $3\ \text{m/s}$. By what factor does $KE$ change?
A $3\ \text{kg}$ cart slows from $6\ \text{m/s}$ to $3\ \text{m/s}$. By what factor does $KE$ change?
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It decreases by a factor of $4$. Initial $KE=54\ \text{J}$, final $KE=13.5\ \text{J}$, so factor is $4$.
It decreases by a factor of $4$. Initial $KE=54\ \text{J}$, final $KE=13.5\ \text{J}$, so factor is $4$.
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Which observation best indicates kinetic energy changed into light energy in an interaction?
Which observation best indicates kinetic energy changed into light energy in an interaction?
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Light is emitted (for example, a spark). KE converts to electromagnetic radiation as light.
Light is emitted (for example, a spark). KE converts to electromagnetic radiation as light.
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Which observation best indicates kinetic energy changed into deformation (internal) energy?
Which observation best indicates kinetic energy changed into deformation (internal) energy?
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Objects bend, dent, or permanently change shape. KE converts to work done in deforming materials.
Objects bend, dent, or permanently change shape. KE converts to work done in deforming materials.
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What is evidence that friction reduced an object’s kinetic energy?
What is evidence that friction reduced an object’s kinetic energy?
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The object slows down and the surface warms. Friction converts KE to thermal energy, reducing speed.
The object slows down and the surface warms. Friction converts KE to thermal energy, reducing speed.
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Which interaction is most likely to increase an object’s kinetic energy: push forward or friction opposite motion?
Which interaction is most likely to increase an object’s kinetic energy: push forward or friction opposite motion?
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A push forward. Force in motion direction increases speed and KE.
A push forward. Force in motion direction increases speed and KE.
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Which interaction is most likely to decrease an object’s kinetic energy: push forward or friction opposite motion?
Which interaction is most likely to decrease an object’s kinetic energy: push forward or friction opposite motion?
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Friction opposite the motion. Friction opposes motion, reducing speed and KE.
Friction opposite the motion. Friction opposes motion, reducing speed and KE.
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Identify the evidence that kinetic energy increased when a force acts in the direction of motion.
Identify the evidence that kinetic energy increased when a force acts in the direction of motion.
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Speed increases after the force acts. Force along motion does positive work, increasing KE.
Speed increases after the force acts. Force along motion does positive work, increasing KE.
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Which observation best indicates kinetic energy changed into thermal energy in an interaction?
Which observation best indicates kinetic energy changed into thermal energy in an interaction?
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The objects or surfaces become warmer. KE converts to thermal energy, increasing temperature.
The objects or surfaces become warmer. KE converts to thermal energy, increasing temperature.
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Identify the evidence that kinetic energy was transferred during a collision.
Identify the evidence that kinetic energy was transferred during a collision.
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One object slows while the other speeds up. KE transfers from the slowing object to the speeding one.
One object slows while the other speeds up. KE transfers from the slowing object to the speeding one.
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