LAW OF INERTIA
Which property determines the amount of inertia an object has?
A. Speed
B. Shape
C. Mass
D. Volume
C. Mass
Which situation demonstrates acceleration?
A. A skateboard speeding up down a gentle slope.
B. A bicycle parked beside the sidewalk.
C. A train moving at a constant speed on a straight track.
D. A person standing still while waiting for a bus.
A. A skateboard speeding up down a gentle slope.
A swimmer pushes the water backward with her hands while swimming forward. Which explanation best describes this motion?
A. The water pushes the swimmer forward with an equal and opposite force.
B. The swimmer pushes harder than the water pushes back.
C. The swimmer moves because the water has less mass.
D. The water only changes direction after the swimmer stops.
A. The water pushes the swimmer forward with an equal and opposite force.
A phone charger is connected to the same wall outlet, but the charging cable is replaced with one that has much higher resistance. If the outlet voltage stays the same, what will most likely happen to the current flowing through the charger?
A. It will increase because more resistance creates more current.
B. It will decrease because greater resistance limits current flow.
C. It will remain the same because voltage determines current alone.
D. It will reverse direction because resistance changes polarity.
B. It will decrease because greater resistance limits current flow.
A passenger places a backpack on the floor of a bus. When the bus suddenly moves forward, the backpack slides toward the back of the bus. Which explanation best accounts for this observation?
A. Gravity shifted toward the rear of the bus.
B. The air inside the bus pulled the backpack backward.
C. The backpack resisted the change from rest because of inertia.
D. The engine pushed the backpack backward more strongly than the bus.
C. The backpack resisted the change from rest because of inertia.
A bus moves around a curved road while maintaining the same speed. Why is the bus accelerating?
A. The engine uses more fuel during the turn.
B. The speed remains constant while turning.
C. Its direction changes even though its speed stays the same.
D. The mass of the bus increases during the turn.
C. Its direction changes even though its speed stays the same.
A person steps off a small boat onto a dock. As the person moves forward, the boat drifts backward. Which statement best explains why the boat moves?
A. The person's weight pulls the boat backward.
B. The dock pushes the boat away from the shore.
C. The boat moves because it has less friction than the dock.
D. The person pushes the boat backward while the boat pushes the person forward.
D. The person pushes the boat backward while the boat pushes the person forward.
An engineer is choosing between two wires made of the same material and kept at the same temperature. One wire is twice as long as the other but has the same thickness.
Which prediction is most reasonable?
A. The longer wire will have greater resistance and allow less current.
B. The longer wire will have lower resistance and allow more current.
C. Both wires will have equal resistance because they use the same material.
D. The longer wire will carry more current because electrons travel farther.
A. The longer wire will have greater resistance and allow less current.
Two identical cars travel at the same speed. One carries four passengers while the other has only the driver. Which prediction is most reasonable?
A. The lighter car has greater inertia.
B. The car with more passengers will require a greater force to stop.
C. Both cars will stop the same way because they have the same speed.
D. The heavier car will stop first because gravity pulls it down more strongly.
B. The car with more passengers will require a greater force to stop.
A box with a mass of 8 kg is pushed with a net force of 40 N. What is its acceleration?
A. 3 m/s²
B. 4 m/s²
C. 4.5 m/s²
D. 5 m/s²
D. 5 m/s²
Two students stand on skateboards facing each other. One student pushes the other. After the push, both students roll away in opposite directions.
Which observation provides the strongest evidence that the interaction follows Newton's Third Law?
A. Both students eventually stop moving because of friction.
B. Both students move in opposite directions immediately after the push.
C. The heavier student always travels the greater distance.
D. The lighter student experiences a stronger action force.
B. Both students move in opposite directions immediately after the push.
Four students discuss how to increase the current flowing through a resistor connected to a battery.
Which student's explanation correctly applies Ohm's Law?
A. Increase the resistance while keeping the voltage constant.
B. Increase the voltage while keeping the resistance constant.
C. Decrease both the voltage and the resistance together.
D. Increase the wire length while keeping the voltage constant.
B. Increase the voltage while keeping the resistance constant.
A child is standing inside a bus that suddenly accelerates. The child loses balance and falls backward. Which explanation best accounts for the motion?
A. Gravity pulled the child backward.
B. The bus pushed the child backward.
C. The child's body resisted the sudden change in motion.
D. Air inside the bus exerted a backward force on the child.
C. The child's body resisted the sudden change in motion.
Four identical carts are pushed with the same net force. Which cart will experience the greatest acceleration?
A - 40kg
B - 30kg
C - 10kg
D - 20kg
A. Cart A because it has the greatest momentum.
B. Cart C because the smallest mass produces the greatest acceleration under the same force.
C. Cart D because its mass provides better stability.
D. Cart B because it has a balanced amount of mass.
B. Cart C because the smallest mass produces the greatest acceleration under the same force.
Four groups explain why a rocket can move upward in space where there is almost no air.
Which group's explanation is scientifically correct?
A. The rocket pushes against the air surrounding Earth.
B. The rocket engine produces more force than gravity at all times.
C. The expelled gases push downward while the gases push the rocket upward with an equal and opposite force.
D. The rocket moves because space has no resistance to oppose its motion.
C. The expelled gases push downward while the gases push the rocket upward with an equal and opposite force.
A factory replaces copper wiring with steel wiring of the same length and thickness to reduce costs. After installation, several machines receive less current than expected.
Which explanation best evaluates the problem?
A. Steel allows electricity to move more easily than copper.
B. Steel has lower conductivity, resulting in greater resistance.
C. Copper produces voltage while steel only stores electrical energy.
D. Steel causes current to reverse direction inside the circuit.
B. Steel has lower conductivity, resulting in greater resistance.
A manufacturer advertises that a new braking system completely eliminates the need for seatbelts. Which evidence would most strongly challenge this claim?
A. Seatbelts make passengers more comfortable.
B. Brakes only reduce the vehicle's motion, not the passengers'.
C. Modern vehicles already have stronger engines than older vehicles.
D. Drivers who wear seatbelts usually travel at lower speeds than others.
B. Brakes only reduce the vehicle's motion, not the passengers'.
Two engineers are improving the performance of identical electric carts. Engineer X suggests increasing the motor's force, while Engineer Y suggests reducing the cart's mass. Which evaluation is most accurate?
A. Only Engineer X is correct because force alone determines acceleration.
B. Both engineers are correct because increasing force or decreasing mass increases acceleration according to Newton's Second Law.
C. Neither engineer is correct because acceleration depends only on speed.
D. Only Engineer Y is correct because mass has a greater effect than force.
B. Both engineers are correct because increasing force or decreasing mass increases acceleration according to Newton's Second Law.
A student claims:
"When a truck collides with a small car, the truck exerts a greater force because the car is more damaged."
Which response best evaluates the student's claim?
A. The truck exerts more force because it has greater mass.
B. The car exerts less force because it changes shape more easily.
C. Both vehicles exert equal and opposite forces, but the smaller car experiences a greater change in motion.
D. The collision forces depend only on the speed of the smaller vehicle.
C. Both vehicles exert equal and opposite forces, but the smaller car experiences a greater change in motion.
A designer wants a heating device to produce more current without changing its resistance. Four proposals are suggested.
Which proposal should the designer choose?
A. Increase the wire length while keeping the voltage unchanged.
B. Replace the wire with a thinner conductor of the same material.
C. Lower the battery voltage while maintaining the same resistance.
D. Use a higher-voltage power source while keeping the resistance constant.
D. Use a higher-voltage power source while keeping the resistance constant.