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Nice work!In summary, Bob needs to apply his brakes 40 meters before a stop sign in order to stop at the sign. This is calculated by using the formula d = (vi+vf)/2 * t, where vi is the initial velocity, vf is the final velocity, and t is the time it takes to come to a stop.
- #1
billybobay
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Homework Statement
When Bob applies the brakes to his car, it slows uniformly from 20.0 m/s to 0.0 m/s in 4.0 s. How many meters before a stop sign must he apply his brakes in order to stop at the sign?
80 m
60 m
40 m
20 m
Homework Equations
d=(20+0)/2(4)
d= 40 m
The Attempt at a Solution
Bob needs 40 m to stop his car.
Would that be correct?
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SammyS
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Yes.
- #3
PotentialE
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Distance = ??
Time = 4s
Velocity initial = 20m/s
Velocity final = 0m/s
Acceleration = ??
A = Vf-Vi / T
A = -20 / 4
A = -5m/ss
D = ViT + ATT/2
D = (20)(4) + (-5)(4)(4) / 2
D = 80 + -40
D = 40m
yes, you're correct
- #4
SammyS
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@ billybobay,
It's perfectly fine to work it out the way you did, using average velocity.
- #5
asteriatic
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Yes, your calculation is correct. Bob would need to apply his brakes 40 meters before the stop sign in order to stop at the sign with a uniform deceleration of 5 m/s^2. This distance can be calculated using the formula d = (v1 + v2)/2 * t, where v1 and v2 are the initial and final velocities, respectively, and t is the time it takes to decelerate. It is important for drivers to be aware of their car's deceleration rate and apply the brakes in a timely manner in order to stop safely at stop signs.
Related to Calculate Distance for Bob to Stop at Stop Sign
1. How do you calculate the distance for Bob to stop at a stop sign?
To calculate the distance for Bob to stop at a stop sign, you first need to know the speed at which Bob is traveling. Then, using the formula d = (v^2)/(2a), where d is the distance, v is the initial velocity, and a is the deceleration, you can calculate the distance needed for Bob to come to a complete stop.
2. What factors affect the distance needed for Bob to stop at a stop sign?
The distance needed for Bob to stop at a stop sign is affected by several factors, including the speed at which Bob is traveling, the weight of his vehicle, the condition of his brakes, and the road conditions (such as wet or icy roads). These factors can impact the deceleration of the vehicle and therefore, the distance needed to come to a stop.
3. Is there a standard distance requirement for stopping at a stop sign?
There is no standard distance requirement for stopping at a stop sign. The distance needed to stop at a stop sign can vary depending on the factors mentioned above. However, most states have laws that require drivers to be able to stop within a certain distance, such as within the distance they can see ahead of them.
4. How can I ensure that I am stopping at the appropriate distance at a stop sign?
To ensure that you are stopping at the appropriate distance at a stop sign, it is important to follow the speed limit and pay attention to road conditions. Additionally, regularly maintaining your vehicle's brakes can help ensure they are functioning properly and can stop your vehicle at the appropriate distance.
5. How does the distance needed for Bob to stop at a stop sign differ for different types of vehicles?
The distance needed for Bob to stop at a stop sign can differ for different types of vehicles. Heavier vehicles may require a longer distance to come to a complete stop, while smaller vehicles may be able to stop in a shorter distance. Additionally, vehicles with newer or more advanced braking systems may be able to stop in a shorter distance compared to older vehicles or those with less advanced braking systems.
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