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kari74 [83]
3 years ago
11

You are driving to the grocery store at 20 m/s. You are 110 m from an intersection when the light turns red. You have a reaction

time of 0.70 seconds before applying the brakes.
a) How far from the intersection are you when you hit the brakes?
b) What deceleration is required to stop at the intersection?
c) How long does it take you to stop?
Physics
1 answer:
Lynna [10]3 years ago
8 0

Answer:

a)

reaction time = 0.70 s

distance travelled in reaction time = v*t

= 20 m/s * 0.70 s

= 14 m

So, when brake is applied, distance remaining= 110 m - 14 m = 96 m

Answer: 96 m

b)

vf = 0 m/s

d = 96 m

vi = 20 m/s

use:

vf^2 = vi^2 + 2*a*d

0 = 20^2 + 2*a*96

-400 = 2*a*96

a = -2.08 m/s^2

Answer: -2.08 m/s^2

c)

use:

vf = vi + a*t

0 = 20 - 2.08*t

t = 9.6 s

Answer: 9.6 s

Explanation:

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Answer:

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The gravity force is highly predictable; it is always in the same direction (down) and always of the same magnitude - mass*9.8 N/kg. The tension force is considerably less predictable. Both its direction and its magnitude change as the bob swings to and fro. The direction of the tension force is always towards the pivot point. So as the bob swings to the left of its equilibrium position, the tension force is at an angle - directed upwards and to the right. And as the bob swings to the right of its equilibrium position, the tension is directed upwards and to the left. The diagram below depicts the direction of these two forces at five different positions over the course of the pendulum's path.

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A rabbit is moving in the positive x-direction at 1.10 m/s when it spots a predator and accelerates to a velocity of 10.9 m/s al
anzhelika [568]

Answer:

aₓ = 0 ,       ay = -6.8125 m / s²

Explanation:

This is an exercise that we can solve with kinematics equations.

Initially the rabbit moves on the x axis with a speed of 1.10 m / s and after seeing the predator acceleration on the y axis, therefore its speed on the x axis remains constant.

x axis

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