How can kinematics problems be solved with reaction time taken into account?

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She took 1.0 s to react and slow down at a rate of 3.0 m/s2. She was able to stop 5.0m before the bridge. It took her 9.3 seconds to stop the car, including her reaction time. The kinematics formula incorporating all the given variables is d = (vi)t + (1/2)a(t^2). In summary, a driver traveling at 25m/s spotted a "Bridge Out Ahead" sign and it took her 1.0 s to react and begin breaking. The car slowed down at a rate of 3.0 m/s2 and
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stphillips
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Homework Statement


1) A driver is traveling at 25m/s when she spots a sign that reads "Bridge Out Ahead". It takes her 1.0 s to react and begin breaking. The car slows down at a rate of 3.0 m/s2. Luckily, she stops 5.0m short of the washed-out bridge.
(a) How much time was required to stop the car when she spotted the sign?
(b) How far was the driver from the bridge when she first noticed the sign(keep in mind her reaction time)

Homework Equations



The Attempt at a Solution


25 m/s / 3m/s2 = 8.3seconds + 1 second (reaction time) = 9.3 seconds.
b)
 
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  • #2
For (b) there is one of the four kinematics that is particularly useful for this problem and many others being that you are given an initial velocity, an acceleration, a final distance, and you just found the time coordinate from completing (a). Which of the kinematics incorporates these all of these variables as well as pertaining to a displacement? That ought to get you in the right direction.

Joe
 

1. What is Kinematics?

Kinematics is the branch of physics that studies the motion of objects and the factors that influence their motion, such as position, velocity, and acceleration.

2. What are the three equations of motion in Kinematics?

The three equations of motion in Kinematics are:

  1. Position: x = x0 + v0t + ½at2
  2. Velocity: v = v0 + at
  3. Acceleration: v2 = v02 + 2a(x-x0)

3. How do you solve Kinematics problems?

To solve Kinematics problems, you need to identify the known and unknown variables, and then use the appropriate equation(s) of motion to solve for the unknown variable(s). It is important to pay attention to units and use consistent units throughout the problem.

4. What is the difference between distance and displacement in Kinematics?

Distance is the total path length traveled by an object, while displacement is the straight-line distance between an object's initial and final positions. Distance is a scalar quantity, while displacement is a vector quantity.

5. How does Kinematics relate to other branches of physics?

Kinematics is closely related to other branches of physics, such as dynamics (the study of forces and their effects on motion) and kinetics (the study of the causes of motion). It also forms the basis for more advanced topics in physics, such as rotational motion and projectile motion.

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