1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Kruka [31]
3 years ago
12

A motorist is driving at 20m/s when she sees that a traffic light 200m ahead has just turned red. She knows that this light stay

s red for 15s, and she wants to reach the light just as it turns green again. It takes her 1.0s to step on the brakes and begin slowing. What is her speed as she reaches the light at the instant it turns green?
Physics
1 answer:
yuradex [85]3 years ago
4 0

Answer:

5.71428571422 m/s

Explanation:

u = Initial velocity = 20 m/s

v = Final velocity

s = Displacement

a = Acceleration

Time taken = 15-1 = 14 s

Distance traveled in 1 second = 20\times 1=20\ m

s=ut+\frac{1}{2}at^2\\\Rightarrow 200-20=20\times 14+\frac{1}{2}\times a\times 14^2\\\Rightarrow a=\frac{2(180-20\times14)}{14^2}\\\Rightarrow a=-1.02040816327\ m/s^2

v=u+at\\\Rightarrow v=20-1.02040816327\times 14\\\Rightarrow v=5.71428571422\ m/s

The speed as she reaches the light at the instant it turns green is 5.71428571422 m/s

You might be interested in
A force of 85 N is used to push a box along the floor a distance of 15 m. How much work was done?
denpristay [2]

Answer:

1275J

Explanation:

Given parameters:

Force on box  = 85N

Distance moved  = 15m

Unknown:

Work done  = ?

Solution:

Work done is the amount of force applied on a body to move it through a specific distance.

 Work done  = Force x distance

Now insert the parameters and solve;

 Work done = 85 x 15  = 1275J

4 0
3 years ago
Read 2 more answers
Which has a greater force: a semi-truck at rest or a moving bicycle?
Wittaler [7]

Although the semi truck certainly has a larger mass, it is not in motion and therefore does not have any momentum. The bicycle however has both mass and velocity and therefore has the larger momentum of the pair.

8 0
3 years ago
Read 2 more answers
Due to the wave nature of light, light shined on a single slit will produce a diffraction pattern? Green light (520 nm) is shine
TiliK225 [7]

Answer:

Yes, it will produce a diffraction pattern.

a. 3.9 mm b. 1.95 mm

Explanation:

The light shined from a single slit will produce a diffraction pattern because,  the wavefront act as wavelets which generates its own wave according to Huygens principle. This therefore causes the diffraction pattern.

Given

wavelength of green light, λ = 520 nm = 520 × 10⁻⁹ m = 5.20 × 10⁻⁷ m

width of slit, d = 0.440 mm = 0.44 × 10⁻³ m = 4.4 × 10⁻⁴ m

Distance of slit from central maximum , D = 1.65 m

Distance of first minimum from central maximum, y = ?

a. The relationship between the slit width and wavelength is given by [tex} dsinθ = mλ [/tex]where d = slit width, θ = angular distance from central maximum, λ = wavelength of light and m = ±1, ±2, ±3...

The relationship between y and D is given by tanθ = y/D

Since θ is small, sinθ ≈ θ ≈ tanθ

so, dθ = mλ ⇒ θ = mλ/d = y/D

Therefore, y = mλD/d

Now, for the first minimum above the slit, m = +1 and for the first minimum below the slit, m = -1. So, y₁ =  λD/d and y₋₁ =  -λD/d. So, the width of the central maximum Δy is the difference between the first minima below and above the central maximum. So, Δy = y₁ - y₋₁ = λD/d -(-λD/d) = 2λD/d

Substituting the values from above, Δy= 2 × 5.20 × 10⁻⁷ × 1.65/4.4 × 10⁻⁴ =  3900 × 10⁻⁶ m = 3.9 × 10⁻³ m = 3.9 mm

b. The first order fringe is the fringe located between the first minimum and the second minimum. From dsinθ = mλ and tanθ = y/D when θ is small, sinθ ≈ θ ≈ tanθ. So, y = mλD/d. Let m= 1 and m=2 be the first and second minima respectively. So,y₁ =  λD/d and y₂ =  2λD/d. The difference Δy₁ = y₂ - y₁ is the width of the first order fringe. Therefore, Δy₁ = 2λD/d - λD/d= λD/d. Substituting the values from above, we have

λD/d= 5.20 × 10⁻⁷ × 1.65/4.4 × 10⁻⁴= 1.95 × 10⁻³ m = 1.95 mm

7 0
3 years ago
12000 inches to yards
Nutka1998 [239]

ANSWER

\begin{equation*} 333.33\text{ yds} \end{equation*}

EXPLANATION

We want to convert 12000 inches to yards.

To do this, divide the value in inches by 36:

\begin{gathered} 1\text{ in }=\frac{1}{36}\text{ yd} \\  \\ 12000\text{ in }=\frac{12000}{36}\text{ yds }=333.33\text{ yds} \end{gathered}

That is the answer.

4 0
1 year ago
KI + Cl2 ---&gt; KCl + I2<br> Balance the single replacement chemical reaction.
snow_lady [41]

Answer:

2KI   +  Cl₂   →   2KCl     +    I₂

Explanation:

The reaction equation is given as:

        KI   +  Cl₂   →    KCl     +    I₂

The problem at hand is to balance this chemical reaction. To solve this problem we use a mathematical approach;

        aKI   +  bCl₂   →    cKCl     +    dI₂

 Conserving K : a = c

                     I :  a  = 2d

                   Cl : 2b = c  

 Now let a = 1, c  = 1 , d  = \frac{1}{2}, b   = \frac{1}{2}, ;

   Multiply through by 2;

             a  = 2, b = 1 , c = 2, d  = 1

 

            2KI   +  Cl₂   →   2KCl     +    I₂

 

5 0
3 years ago
Other questions:
  • A uniformly charged rod (length = 2.0 m, charge per unit length = 5.0 nc/m) is bent to form one quadrant of a circle. what is th
    15·1 answer
  • The atmospheric pressure in denver, co is 633 mmhg. what is this pressure in atm?
    7·1 answer
  • Any energy transformation involves the loss of some energy as
    5·2 answers
  • A 60 kg student is standing in the train station next to her 10 kg suitcase when her train is called. (A) Estimate how much work
    9·1 answer
  • What is genetic energy and what is potential energy
    13·2 answers
  • 12. Which of these is more dense?
    10·1 answer
  • If velocity is positive, which would most likely yield a negative acceleration?
    10·1 answer
  • According to Newton’s first law, only ___ has the ability to change motion.
    5·1 answer
  • 8TH GRADE SCIENCE PLEASE HELPPP
    7·1 answer
  • If the same force is applied to an object with a small mass it will have a
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!