Which graph BEST represents the relationship between velocity and time for an object that accelerates uniformly for 2 seconds, then moves at a constant velocity for 1 second, and finally decelerates for 3 seconds?
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The best graph to represent the relationship between velocity and time for the given situation would be a piecewise graph. The graph would show a linear increase in velocity for the first 2 seconds, indicating uniform acceleration. Then, there would be a horizontal line at a constant velocity for the next 1 second, indicating constant velocity. Finally, there would be a linear decrease in velocity for the next 3 seconds, indicating deceleration.
The graph can be broken down into three sections:
1) Acceleration Phase: The object accelerates uniformly for 2 seconds. The graph will show a straight line with a positive slope indicating the increasing velocity with time.
2) Constant Velocity Phase: The object moves at a constant velocity for 1 second. The graph will show a horizontal line at a certain velocity.
3) Deceleration Phase: The object decelerates for 3 seconds. The graph will show a straight line with a negative slope indicating the decreasing velocity with time.
Therefore, the best graph that represents this relationship is a graph with a positive slope for 2 seconds, followed by a horizontal line for 1 second, and then a negative slope for 3 seconds.
To determine the graph that best represents the relationship between velocity and time for the given scenario, let's break down the motion into its different phases:
1. Acceleration for 2 seconds: During this phase, the object is accelerating uniformly. This means its velocity is increasing at a constant rate. The graph for this phase would be a straight line with a positive slope, indicating a positive and increasing velocity.
2. Constant velocity for 1 second: After accelerating, the object maintains a constant velocity for 1 second. This means its velocity remains constant and does not change. The graph for this phase would be a horizontal line, indicating a constant velocity.
3. Deceleration for 3 seconds: In the final phase, the object decelerates, meaning its velocity decreases at a constant rate. The graph for this phase would be a straight line with a negative slope, indicating a negative and decreasing velocity.
Now, let's put it all together:
Starting at time t = 0, the graph will have a positive slope (representing acceleration) for the first 2 seconds. Then, it will stay horizontal (representing constant velocity) for the next 1 second. Finally, it will have a negative slope (representing deceleration) for the next 3 seconds.
Therefore, the graph that best represents the relationship between velocity and time for the given scenario would be a straight line with a positive slope for the first 2 seconds, followed by a horizontal line for 1 second, and then a straight line with a negative slope for the next 3 seconds.
Airbags are safety devices designed to protect vehicle occupants during collisions by reducing the impact forces exerted on their bodies. The fundamental principle behind airbags is the concept of rapid inflation and deflation. When a collision occurs, sensors in the vehicle detect the sudden deceleration and send a signal to the airbag control unit. The control unit then triggers the inflation system.
The inflation system of an airbag consists of a solid-state propellant, typically sodium azide, and a mixture of other chemicals. Upon activation, an electric current passes through the propellant, causing it to rapidly decompose and release nitrogen gas. This gas inflates the airbag in milliseconds, allowing it to cushion the vehicle occupant's forward motion and prevent direct contact with hard surfaces, such as the steering wheel or dashboard. The airbag deflates quickly after inflation to allow the occupant to exit the vehicle safely. The entire process occurs in a fraction of a second, providing a protective barrier and reducing the risk of severe injuries, particularly head and chest injuries, during a collision.
VII. Reading & Evidence Questions:
13. Using the text above, how does an airbag work and why does it have to work so quickly?
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14. How does inertia play a role during a car accident, and what tools are in place to keep us safe?
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13. An airbag works by rapidly inflating and deflating to cushion the vehicle occupant's forward motion during a collision. It works quickly because it needs to deploy almost instantaneously after the collision is detected in order to provide a protective barrier and reduce the impact forces on the occupant's body. The rapid inflation and deflation process occurs within milliseconds to effectively mitigate the risk of severe injuries.
14. Inertia plays a role during a car accident because it is the tendency of objects to resist changes in their state of motion. When a car suddenly decelerates or collides with another object, the occupants continue to move forward at their current speed due to inertia. To keep us safe, tools like seat belts and airbags are in place. Seat belts restrain the occupant's body and prevent them from being thrown forward, while airbags provide a cushioning effect to absorb and dissipate the energy of the forward motion. Together, seat belts and airbags help reduce the impact forces exerted on the occupants, minimizing the risk of severe injuries.