Newton's First & Second Laws quiz #5 Flashcards
Newton's First & Second Laws quiz #5
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In a frontal collision, what principle explains the motion of passengers? Inertia explains why passengers continue moving forward during a frontal collision. When you change directions or speed too rapidly, what effect does inertia have on the vehicle? Inertia causes the vehicle to resist the change, potentially leading to loss of control. To overcome an object's inertia, what must act upon it? A net external force must act upon the object. Vehicle skids are most likely to be caused by what? Unbalanced forces and loss of traction cause vehicle skids. What is the tendency of an object to resist change called? This tendency is called inertia. What is the sum of all forces acting on an object called? The sum of all forces is called the net force. Any external force that acts against movement is called what? It is called resistance or friction. What are the three basic steps in collision prevention? Recognize the hazard, understand the defense, and act correctly in time. Explain how Newton's law of inertia describes the motion of objects. Newton's law of inertia states that objects resist changes in their motion unless acted upon by a net force. Equal forces acting on an object in opposite directions result in what? They result in balanced forces and no change in motion. Suddenly steering to the right will result in what effect due to inertia? Inertia will cause the vehicle to resist the change, possibly leading to loss of control. Strong winds causing a vehicle to lose all control is called what? It is called a spinout, caused by unbalanced forces. When driving through a curve at normal speed, what effect does inertia have? Inertia resists the change in direction, requiring friction to keep the vehicle on the curve. Stopping a vehicle with good brakes from 20 miles per hour under good conditions requires about what? It requires a certain distance, determined by the vehicle's mass, speed, and braking force. Understeer results from what? Understeer results from insufficient front tire traction, causing the vehicle to resist turning. A bicyclist pedaling up a hill is an example of what? It is an example of applying an unbalanced force to overcome gravity. Controlled braking is what? Controlled braking is applying the brakes smoothly to avoid skidding and maintain control. When an object has its motion changed, what is generally the cause? A net (unbalanced) force is generally the cause. Resistance is a force that does what? Resistance opposes motion. Including reaction time, what affects stopping distance? Reaction time, speed, and braking force affect stopping distance. Air bags deploy at speeds up to what? Air bags deploy at speeds sufficient to cause injury in a collision, typically above a certain threshold. Forces always occur in what manner? Forces always occur in pairs, as described by Newton's third law. Rapid deceleration of the head, such as when it impacts the windshield, causes what? It causes injury due to the sudden change in motion (acceleration). Your car is skidding to a stop from a high speed. What principle explains the motion? Inertia explains why the car continues moving until friction slows it down. You can minimize the effect of inertia on your body while driving by doing what? Wearing a seatbelt minimizes the effect of inertia during sudden stops. How do you find net force? Add all forces acting on the object, considering their directions. Can there be forces acting on an object at rest? Yes, but if they are balanced, the object remains at rest. A vertical pull of a heavy cable from the top down is likely to require what? It requires a force equal to the weight of the cable and any attached load. If an approaching train is near enough to be a danger, what should you do? You should stop and wait for the train to pass. If two vehicles arrive at an uncontrolled intersection at the same time, what determines who goes first? Right-of-way rules determine who goes first. If you have a tire blowout, then you do not want to quickly accelerate or do what? You do not want to brake hard. An object in motion stays in motion unless what? Unless acted upon by a net external force. How do you find applied force? Applied force is the force exerted by a person or object on another object. Sum of all forces acting on an object is called what? It is called the net force. Determine the x-component of the force on the electron. The x-component is found by multiplying the force magnitude by the cosine of the angle with respect to the x-axis. Why does the airbag inflate and deflate quickly? To reduce the force and acceleration experienced by the passenger during a collision. Newton's second law says that when an unbalanced force acts on an object, what happens? The object accelerates in the direction of the net force. What is the physical force affecting the body's ability to create force, accelerate, and decelerate? The net force acting on the body affects its ability to accelerate and decelerate. If a block is moving to the left at constant velocity, what can one conclude? The forces acting on the block are balanced; net force is zero. Based on Newton’s second law, will walking be an effective way to build muscle? Walking applies force, but greater force (such as running or lifting) is needed for significant muscle building.
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