Reduce Collision Effects - Middle School Physical Science
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What is the key design goal of a crumple zone in a car during a collision?
What is the key design goal of a crumple zone in a car during a collision?
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Increase stopping time $\Delta t$ to reduce force. Deforms to extend collision time, reducing peak forces.
Increase stopping time $\Delta t$ to reduce force. Deforms to extend collision time, reducing peak forces.
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What is the main safety purpose of an airbag during a crash?
What is the main safety purpose of an airbag during a crash?
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Increase $\Delta t$ and spread force over larger area. Cushions impact and distributes force over body surface.
Increase $\Delta t$ and spread force over larger area. Cushions impact and distributes force over body surface.
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What is the main safety purpose of a seat belt during a crash?
What is the main safety purpose of a seat belt during a crash?
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Increase $\Delta t$ and prevent impact with interior. Restrains body to decelerate with car over longer time.
Increase $\Delta t$ and prevent impact with interior. Restrains body to decelerate with car over longer time.
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What is the correct design principle for helmets to reduce head injury in impacts?
What is the correct design principle for helmets to reduce head injury in impacts?
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Hard shell + foam liner to increase $\Delta t$ and spread force. Shell protects while foam extends impact time.
Hard shell + foam liner to increase $\Delta t$ and spread force. Shell protects while foam extends impact time.
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What is the kinetic energy formula relevant to damage in high-speed collisions?
What is the kinetic energy formula relevant to damage in high-speed collisions?
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$KE=\frac{1}{2}mv^2$. Energy increases with square of velocity.
$KE=\frac{1}{2}mv^2$. Energy increases with square of velocity.
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If speed doubles, by what factor does $KE$ change according to $KE=\frac{1}{2}mv^2$?
If speed doubles, by what factor does $KE$ change according to $KE=\frac{1}{2}mv^2$?
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It becomes $4$ times larger. KE proportional to $v^2$, so doubling $v$ quadruples KE.
It becomes $4$ times larger. KE proportional to $v^2$, so doubling $v$ quadruples KE.
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What is Newton's third law statement that applies to forces during a collision?
What is Newton's third law statement that applies to forces during a collision?
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Forces are equal in magnitude and opposite in direction. Action-reaction pairs exist between colliding objects.
Forces are equal in magnitude and opposite in direction. Action-reaction pairs exist between colliding objects.
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During a collision, are the forces on object A and object B equal or is one larger?
During a collision, are the forces on object A and object B equal or is one larger?
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Equal in magnitude; opposite in direction. Newton's third law requires equal and opposite forces.
Equal in magnitude; opposite in direction. Newton's third law requires equal and opposite forces.
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What design feature reduces injury by increasing stopping distance for a falling object or person?
What design feature reduces injury by increasing stopping distance for a falling object or person?
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Cushioning that increases stopping distance and $\Delta t$. Soft materials compress to extend deceleration time.
Cushioning that increases stopping distance and $\Delta t$. Soft materials compress to extend deceleration time.
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Which material choice best reduces collision force: rigid steel plate or compressible foam pad?
Which material choice best reduces collision force: rigid steel plate or compressible foam pad?
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Compressible foam pad. Foam compresses to increase $\Delta t$, reducing force.
Compressible foam pad. Foam compresses to increase $\Delta t$, reducing force.
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Identify the best design change to reduce force: add padding or remove padding (same crash speed).
Identify the best design change to reduce force: add padding or remove padding (same crash speed).
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Add padding. Padding increases collision time, reducing impact force.
Add padding. Padding increases collision time, reducing impact force.
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What is a common design strategy to reduce pressure on the body during impact?
What is a common design strategy to reduce pressure on the body during impact?
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Increase contact area to reduce pressure. Spreading force over larger area reduces pressure and injury risk.
Increase contact area to reduce pressure. Spreading force over larger area reduces pressure and injury risk.
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What is the pressure formula used to connect force spreading to injury reduction?
What is the pressure formula used to connect force spreading to injury reduction?
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$P=\frac{F}{A}$. Pressure equals force divided by contact area.
$P=\frac{F}{A}$. Pressure equals force divided by contact area.
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If the same force is spread over $2$ times the area, what happens to pressure $P$?
If the same force is spread over $2$ times the area, what happens to pressure $P$?
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It becomes $\frac{1}{2}$ as large. Doubling area halves pressure since $P=F/A$.
It becomes $\frac{1}{2}$ as large. Doubling area halves pressure since $P=F/A$.
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Identify the design feature that reduces injury by preventing occupants from striking hard surfaces: seat belt or rigid dashboard?
Identify the design feature that reduces injury by preventing occupants from striking hard surfaces: seat belt or rigid dashboard?
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Seat belt. Restrains occupants to prevent secondary impacts with interior surfaces.
Seat belt. Restrains occupants to prevent secondary impacts with interior surfaces.
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What is Newton's third law statement that applies during a collision?
What is Newton's third law statement that applies during a collision?
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Forces are equal in magnitude and opposite in direction. Action-reaction pairs exist between colliding objects.
Forces are equal in magnitude and opposite in direction. Action-reaction pairs exist between colliding objects.
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What is the key safety idea behind airbags and crumple zones in collisions?
What is the key safety idea behind airbags and crumple zones in collisions?
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Increase stopping time to reduce $F_{avg}$. Extending collision time reduces average force by the impulse-momentum theorem.
Increase stopping time to reduce $F_{avg}$. Extending collision time reduces average force by the impulse-momentum theorem.
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Which design choice reduces collision force more for the same $\Delta p$: a stiff bumper or a crumple zone?
Which design choice reduces collision force more for the same $\Delta p$: a stiff bumper or a crumple zone?
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A crumple zone. Deforms to increase collision time, reducing average force.
A crumple zone. Deforms to increase collision time, reducing average force.
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If the collision force on two objects is the same, which object has greater acceleration: smaller $m$ or larger $m$?
If the collision force on two objects is the same, which object has greater acceleration: smaller $m$ or larger $m$?
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Smaller $m$. Same force on smaller mass produces larger acceleration by $a=F/m$.
Smaller $m$. Same force on smaller mass produces larger acceleration by $a=F/m$.
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What is the formula for acceleration that links force and mass during a collision?
What is the formula for acceleration that links force and mass during a collision?
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$a=\frac{F}{m}$. Newton's second law relates force, mass, and acceleration.
$a=\frac{F}{m}$. Newton's second law relates force, mass, and acceleration.
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During a collision, which is always equal for both objects: force magnitude or acceleration magnitude?
During a collision, which is always equal for both objects: force magnitude or acceleration magnitude?
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Force magnitude. Newton's third law ensures equal forces, but $a=F/m$ varies with mass.
Force magnitude. Newton's third law ensures equal forces, but $a=F/m$ varies with mass.
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What is the formula for kinetic energy that helps compare collision damage potential?
What is the formula for kinetic energy that helps compare collision damage potential?
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$KE=\frac{1}{2}mv^2$. Kinetic energy depends on mass and velocity squared.
$KE=\frac{1}{2}mv^2$. Kinetic energy depends on mass and velocity squared.
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If speed doubles and mass stays the same, by what factor does $KE$ change?
If speed doubles and mass stays the same, by what factor does $KE$ change?
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It becomes $4$ times larger. KE is proportional to $v^2$, so doubling $v$ quadruples KE.
It becomes $4$ times larger. KE is proportional to $v^2$, so doubling $v$ quadruples KE.
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Which design choice best reduces injury by spreading force over area: sharp point or wide pad?
Which design choice best reduces injury by spreading force over area: sharp point or wide pad?
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Wide pad (larger contact area). Distributes force over larger area, reducing pressure.
Wide pad (larger contact area). Distributes force over larger area, reducing pressure.
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What is the main reason padding reduces injury even if it does not change $\Delta p$?
What is the main reason padding reduces injury even if it does not change $\Delta p$?
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It lowers $F_{avg}$ by increasing $\Delta t$. Same momentum change over longer time means less force.
It lowers $F_{avg}$ by increasing $\Delta t$. Same momentum change over longer time means less force.
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