/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 26 In the Daytona 500 auto race, a ... [FREE SOLUTION] | 91Ó°ÊÓ

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In the Daytona 500 auto race, a Ford Thunderbird and a Mercedes Benz are moving side by side down a straightaway at \(71.5 \mathrm{m} / \mathrm{s} .\) The driver of the Thunderbird realizes he must make a pit stop, and he smoothly slows to a stop over a distance of \(250 \mathrm{m}\). He spends \(5.00 \mathrm{s}\) in the pit and then accelerates out, reaching his previous speed of \(71.5 \mathrm{m} / \mathrm{s}\) after a distance of \(350 \mathrm{m} .\) At this point, how far has the Thunderbird fallen behind the Mercedes Benz, which has continued at a constant speed?

Short Answer

Expert verified
The distance that the Thunderbird has fallen behind the Mercedes Benz, which has continued at a constant speed, can be calculated using the total time taken by the Thunderbird for deceleration, pitstop, and acceleration, and multiplying that by the speed of the Mercedes.

Step by step solution

01

Calculate Time to Stop

First calculate the time taken by the Thunderbird to stop. Use the equation \( v^2 = u^2 − 2ad \), where \( v = 0 \mathrm{m/s} \) (final speed), \( u = 71.5 \mathrm{m/s} \) (initial speed), and \( d = 250 \mathrm{m} \) (distance). Solving this, we get \( a = −(u^2) / (2d) \). Now with \( v = u + at \), we isolate \( t = (v − u) / a \), giving the time to stop.
02

Calculate Time to Reach Speed again

Now we consider the time taken to get back to the initial speed. The situation is the same as the deceleration, just with positive acceleration instead of negative. So, we use the same equation to find the acceleration and time to reach the speed of \(71.5 \mathrm{m/s}\) again.
03

Calculate Total Time and Distance

Now add the time taken to stop, time spent at the pitstop, and time taken to accelerate again to get total time. Since the Mercedes has been moving at a constant speed, multiply its speed by the total time to find how much farther it has gone over the Thunderbird.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Acceleration
Acceleration is the process by which an object increases its velocity. In the context of the exercise, the Thunderbird had to accelerate to regain its previous speed of \(71.5\, \mathrm{m/s}\) after a pit stop. This was done over a distance of \(350\, \mathrm{m}\).
To calculate acceleration, one can use the formula \(v^2 = u^2 + 2ad\), where \(v\) is the final velocity, \(u\) is the initial velocity (in this case, \(0\, \mathrm{m/s}\) as the car starts from rest), \(a\) is acceleration, and \(d\) is distance. Here, the implication is that the Thunderbird increased its speed steadily over the \(350\, \mathrm{m}\). The value of \(a\) would essentially tell us how quickly the car picked up pace again.
  • A positive acceleration means the object is speeding up.
  • The unit of acceleration is typically \(\mathrm{m/s^2}\).
  • Knowing \(a\) helps in computing time through \(v = u + at\).
This concept is pivotal in understanding changes in motion as a result of forces applied to a body, such as the car's engine power propelling it forward.
Deceleration
Deceleration is simply negative acceleration, a decrease in speed over time. In the problem, we saw this when the Thunderbird needed to make a pit stop. It smoothly slowed down to a stop from \(71.5\, \mathrm{m/s}\) over a distance of \(250\, \mathrm{m}\).
Utilizing the same kinematic equations, deceleration can also be described as:\(v^2 = u^2 - 2ad\), where:
  • \(v\) is the final velocity, or \(0\, \mathrm{m/s}\) when stopped.
  • \(u\) is the initial velocity, \(71.5\, \mathrm{m/s}\)..
  • \(d\) represents distance being \(250\, \mathrm{m}\)..
  • \(a\) will come out negative, indicating deceleration.
Similarly, once \(a\) is determined, the time to stop \(t\) can be calculated using \(t = (v - u) / a\). Understanding deceleration allows us to explore how quickly an object can come to rest, crucial for safety and strategy in racing events.
Pit Stop
A pit stop in racing is an opportunity for quick adjustments, refueling or repairs. It is a strategic pause that can impact the race outcome. In the problem scenario, the Thunderbird took a pit stop lasting \(5.00\, \mathrm{s}\).
While the car was stationary during this time, the Mercedes Benz continued moving at a constant speed. Factors to consider in a pit stop include:
  • The duration of the stop, as every second counts during a race.
  • The tasks to be performed during the stop to limit downtime.
  • The impact on race strategy, such as how much behind it might put the racer.
The pit stop showcases the balancing act between maintaining car performance and minimizing time lost, pivotal in high-speed races like Daytona 500.
Relative Motion
Relative motion refers to the motion of an object as observed from another moving object. In our problem, the relative motion between the Thunderbird and the Mercedes Benz is key.
While the Thunderbird decelerates and stops for a pit, the Mercedes Benz maintains a constant velocity. Relative motion allows us to compare the speed and distance between the two, calculating how far apart they end up after all maneuvers.
For the Thunderbird, total time includes:
  • The deceleration time, where the pit stop effort began.
  • The \(5.00\, \mathrm{s}\) at rest during the pit stop.
  • The acceleration time to reach back previous speed.
The Mercedes Benz continues uninterrupted. By evaluating the total time and speed, one computes the cumulative distance traveled by the Mercedes and compares it with the stopped-and-resumed journey of the Thunderbird. This comparison demonstrates how initial speed differences and regular motions impact relative positions.

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Most popular questions from this chapter

A baseball is hit so that it travels straight upward after being struck by the bat. A fan observes that it takes 3.00 s for the ball to reach its maximum height. Find (a) its initial velocity and (b) the height it reaches.

A truck on a straight road starts from rest, accelerating at \(2.00 \mathrm{m} / \mathrm{s}^{2}\) until it reaches a speed of \(20.0 \mathrm{m} / \mathrm{s} .\) Then the truck travels for \(20.0 \mathrm{s}\) at constant speed until the brakes are applied, stopping the truck in a uniform manner in an additional \(5.00 \mathrm{s}\). (a) How long is the truck in motion? (b) What is the average velocity of the truck for the motion described?

The speed of a bullet as it travels down the barrel of a rifle toward the opening is given by \(v=\left(-5.00 \times 10^{7}\right) t^{2}+\) \(\left(3.00 \times 10^{5}\right) t,\) where \(v\) is in meters per second and \(t\) is in seconds. The acceleration of the bullet just as it leaves the barrel is zero. (a) Determine the acceleration and position of the bullet as a function of time when the bullet is in the barrel. (b) Determine the length of time the bullet is accelerated. (c) Find the speed at which the bullet leaves the barrel. (d) What is the length of the barrel?

Draw motion diagrams for (a) an object moving to the right at constant speed, (b) an object moving to the right and speeding up at a constant rate, \((c)\) an object moving to the right and slowing down at a constant rate, (d) an object moving to the left and speeding up at a constant rate, and (e) an object moving to the left and slowing down at a constant rate. (f) How would your drawings change if the changes in speed were not uniform; that is, if the speed were not changing at a constant rate?

A car has an initial velocity \(v_{0}\) when the driver sees an obstacle in the road in front of him. His reaction time is \(\Delta t_{r}\) and the braking acceleration of the car is \(a\). Show that the total stopping distance is $$s_{\text {stop }}=v_{0} \Delta t_{r}-v_{0}^{2} / 2 a$$,Remember that \(a\) is a negative number.

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