AP Physics 1:: Momentum

What is LINEAR MOMENTUM, and what is the mathematical FORMULA relating an object's momentum to its MASS and VELOCITY?

- **A)** Momentum is a SCALAR quantity with no associated direction, unlike velocity which is a vector
- **B)** Momentum is calculated as p = m/v (mass divided by velocity), rather than mass multiplied by velocity
- **C)** Momentum is a VECTOR quantity representing an object's 'quantity of motion'; p = m*v (mass multiplied by velocity) -- momentum points in the SAME direction as the object's velocity
- **D)** This concept has no actual mathematical relationship between an object's momentum, its mass, and its velocity

What is the SI (metric) UNIT for LINEAR MOMENTUM, and how does this unit relate to the base units of mass and velocity?

- **A)** Kilogram-meters-per-second (kg*m/s) -- directly reflecting momentum's definition as mass (kg) multiplied by velocity (m/s)
- **B)** Momentum is measured in NEWTONS, identical to the unit for force, with no distinct unit of its own
- **C)** The SI unit for momentum is the JOULE, rather than kg*m/s
- **D)** This concept has no actual relationship between the SI unit for momentum and the base units of mass and velocity

What is IMPULSE, and what is the mathematical FORMULA relating impulse to a FORCE and the TIME INTERVAL over which that force acts?

- **A)** This concept has no actual mathematical relationship between impulse, an applied force, and the time interval over which it acts
- **B)** Impulse is the PRODUCT of a force and the time interval over which it acts; J = F*delta_t -- like momentum, impulse is a VECTOR quantity, pointing in the same direction as the applied (net) force
- **C)** Impulse is calculated as J = F/delta_t (force divided by time interval), rather than force multiplied by time interval
- **D)** Impulse depends only on the TIME INTERVAL, with the applied force's magnitude playing no actual role in calculating impulse

What is the IMPULSE-MOMENTUM THEOREM, and what does it state about the relationship between the IMPULSE delivered to an object and the resulting CHANGE in that object's momentum?

- **A)** This theorem has no actual mathematical relationship between impulse delivered to an object and its resulting change in momentum
- **B)** Impulse delivered to an object is always ZERO regardless of how much its momentum actually changes, contradicting the impulse-momentum theorem
- **C)** The impulse-momentum theorem states that impulse always equals an object's TOTAL kinetic energy, rather than its change in momentum
- **D)** The impulse-momentum theorem states that the impulse delivered to an object EQUALS the CHANGE in that object's momentum: J = delta_p = m*delta_v -- this follows directly from combining J=F*delta_t with Newton's second law, F=ma

How can the IMPULSE-MOMENTUM THEOREM explain WHY extending the TIME of impact (e.g., bending your knees when landing a jump, or a car's crumple zone during a collision) REDUCES the AVERAGE FORCE experienced during that impact?

- **A)** The impulse-momentum theorem states that force and time interval are completely INDEPENDENT of each other for a given momentum change
- **B)** This concept has no actual relationship between the duration of an impact and the average force experienced during that impact
- **C)** Extending the time of impact INCREASES the average force experienced, the reverse of the actual relationship described by the impulse-momentum theorem
- **D)** Since impulse (J = F*delta_t) must equal a FIXED momentum change (delta_p) for a given collision, INCREASING the time interval (delta_t) over which that impulse is delivered REQUIRES a correspondingly SMALLER average force (F) to produce the same impulse

What is the LAW OF CONSERVATION OF MOMENTUM, and under what specific CONDITION does the TOTAL momentum of a system of objects remain CONSTANT?

- **A)** Conservation of momentum requires that EACH INDIVIDUAL object's momentum remains SEPARATELY constant, rather than the TOTAL momentum of the system remaining constant
- **B)** Momentum is conserved under ALL circumstances, even when significant NET EXTERNAL forces act on a system
- **C)** The law of conservation of momentum states that the TOTAL momentum of a system remains CONSTANT, provided NO NET EXTERNAL FORCE acts on that system (i.e., the system is 'closed' or 'isolated') -- momentum can be TRANSFERRED between objects WITHIN the system, but the TOTAL remains unchanged
- **D)** This law has no actual relationship to a specific condition (absence of net external force) required for a system's total momentum to be conserved

Why does momentum conservation apply to a system of TWO objects COLLIDING with each other, even though EACH INDIVIDUAL object experiences a large internal collision force during the impact?

- **A)** The collision forces the two objects exert on EACH OTHER are INTERNAL to the two-object system (equal and opposite, per Newton's third law) and therefore CANCEL OUT when considering the system's TOTAL momentum -- as long as no additional EXTERNAL force (like friction from outside the system) acts, total momentum is conserved
- **B)** This concept has no actual relationship between Newton's third law (internal, equal-and-opposite forces) and why total momentum is conserved during a collision
- **C)** Momentum conservation does NOT actually apply during collisions, since the internal collision forces are too large to ignore
- **D)** Momentum conservation during a collision requires that BOTH objects have IDENTICAL mass, with no other condition being relevant

What is a PERFECTLY ELASTIC COLLISION, and what TWO quantities are BOTH conserved during such a collision?

- **A)** A perfectly elastic collision conserves kinetic energy but NOT momentum, the reverse of the correct definition
- **B)** A perfectly elastic collision conserves momentum but NOT kinetic energy, with kinetic energy always decreasing significantly
- **C)** A collision in which BOTH total momentum AND total kinetic energy are conserved (unchanged before and after the collision) -- objects bounce off each other without any permanent deformation or energy loss to heat/sound
- **D)** This concept has no actual relationship between a collision being 'elastic' and which quantities remain conserved during that collision