Math Problem Statement
You're driving down the highway late one night at 20 m/s when a deer steps onto the road 60 m in front of you. Your reaction time before stepping on the brakes is 0.50 s , and the maximum deceleration of your car is 10 m/s2. What is the maximum speed you could have and still not hit the deer?
Solution
To solve this problem, we need to break it into two phases:
- Phase 1: Reaction Time - During the reaction time of 0.50 seconds, the car continues moving at a constant speed before the brakes are applied.
- Phase 2: Braking - After the reaction time, the car decelerates at a rate of until it comes to a stop.
Step 1: Distance covered during reaction time
The car is moving at 20 m/s before the brakes are applied, and during the reaction time of 0.50 seconds, it travels a distance given by:
So, during the reaction time, the car travels 10 meters.
Step 2: Remaining distance for braking
The total distance to the deer is 60 meters. After the reaction time, the remaining distance for braking is:
Step 3: Maximum speed at which the car can stop within the remaining distance
Using the kinematic equation for deceleration: where:
- (final velocity when the car stops),
- is the initial velocity (the speed right before braking),
- (deceleration),
- (remaining distance).
Rearranging the equation to solve for :
Conclusion:
The maximum speed you could have and still not hit the deer is approximately 31.62 m/s.
Would you like more details on any part of the solution?
Here are 5 related questions:
- What would happen if the deceleration was less than 10 m/s²?
- How would the result change if your reaction time was longer?
- What if the deer was closer, say 40 m away instead of 60 m?
- How does the braking distance depend on speed in general?
- What if the road conditions made the deceleration less effective, like in rain?
Tip: Always be aware of the total stopping distance, which includes both the reaction distance and the braking distance.
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Math Problem Analysis
Mathematical Concepts
Kinematics
Deceleration
Motion Equations
Formulas
d_reaction = v_initial * t_reaction
v_f² = v_i² + 2 * a * d
Theorems
Kinematic equations for uniformly accelerated motion
Suitable Grade Level
Grades 9-12
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