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
Ede4ka [16]
3 years ago
10

a police officer finds 60 m of skid marks at the scene of a car crash. Assuming a uniform deceleration of 7.5 m/s to a stop , wh

at was the velocity of the car when it started skidding?
Physics
1 answer:
Oliga [24]3 years ago
6 0
The equation to be used is for the rectilinear motion at constant acceleration:

x = v₀t + 0.5at²
a = (v-v₀)/t
where
x is distance
v and v₀ is the final and initial velocity
t is time
a is acceleration

Because the acceleration is decelerating, that would be reported as -7.5 m/s². Substituting,

-7.5 = (0 - v₀)/t
v₀ = 7.5 t --> eqn 1

x = v₀t + 0.5at²
60 = (7.5t)(t) + 0.5(-7.5)(t²)
Solving for t,
t = 4s

Thus,
v₀ = 7.5 m/s² * 4s
v₀ = 30 m/s
You might be interested in
The star Betelgeuse is 6.1 x 10^18 m away from Earth. How old is the light we see from that star when it reaches us? There are 3
castortr0y [4]

Answer:

635 years old

Explanation:

The light reaching the earth from the sun will travel at a speed called the speed of light, and this has a universal value of 3 × 10⁸ m/s. Bearing this in mind, let us calculate the age of the light reaching the Earth from the sun:

Distance of star from Earth = 6.1 × 10⁸m

Speed of light = 3 × 10⁸ m/s

We have distance and speed, let us calculate the time of travel of the light from the star to the earth.

Distance = speed × time

6.1 × 10⁸ = 3 × 10⁸ × time

time = \frac{6.1 \times 10^{18}}{3 \times 10^8}

In order to do the division above, we will divide the whole numbers normally, then we will apply the law of indices to the power that says:

Xᵃ ÷ Xᵇ = X⁽ᵃ⁻ᵇ⁾

\therefore time = \frac{6.1 \times 10^{18}}{3 \times 10^8}\\= \frac{2.03 \times 10^{(18-8)}}{1} \\= 2.03 \times 10^{10}}\ seconds

Next, we are told that there are 3.2 × 10⁷ seconds in a year.

∴ The number of years travelled by the light from the star:

3.2\ \times 10^7\ seconds = 1\ year\\1\ second =  \frac{1}{3.2\ \times 10^7} \\\therefore 2.03 \times 10^{10}\ seconds = \frac{2.03 \times 10^{10}}{3.2\ \times 10^7}

please note that:

2.03 × 10¹⁰ = 20300000000

3.2 × 10⁷ = 32000000

\therefore \frac{2.03 \times 10^{10}}{3.2\ \times 10^7}\\= \frac{20300000000}{32000000} \\\\= \frac{20300}{32} \\= 634.347\ years\\

The closest answer in the option is 635 years, and we are short of this by some points due probably to approximations in the calculation.

8 0
3 years ago
A light bulb has a power rating of 60 W. What is the current running into it if it is plugged into a 120 V outlet?
kifflom [539]

Answer:

0.5 Amperes

Explanation:

Information that we have:

Power: P=60W

Voltage: V=120V

and we use the equation that relates this two quantities to the Current (I):

I=\frac{P}{V}

where I is the curent, P is the Power and V is the Voltage.

we substitute the values given for the Power and the Voltage to find the current:

I=\frac{60W}{120V}\\ I=0.5A

the Current running into the bulb is 0.5 Amperes

3 0
3 years ago
HELP!!! HURRY!!!!! 100 POINTS!!!!!!!!!
bagirrra123 [75]

what happens at Point C is sublimation. the increase in temperature affects the Vapour pressure soon as you can see the curve is increasing with increasing pressure there is increase in temperature that is the sublimation Curve

7 0
3 years ago
Read 2 more answers
You are holding one end of an elastic cord that is fastened to a wall 3.0 m away. You begin shaking the end of the cord at 2.3 H
Karo-lina-s [1.5K]

Answer:

Time take to fill the standing wave to the entire length of the string is 1.3 sec.

Explanation:

Given :

The length of the one end x= 3m, frequency of the wave f = 2.3 Hz, wavelength of the wave λ = 1 m.

Standing wave is the example of the transverse wave, standing wave doesn't transfer energy in a medium.

We know,

∴ v = fλ

Where v = speed of the standing wave.

also, ∴ v=\frac{x}{t}

where t = time take to fill entire length of the string.

Compare above both equation,

⇒   t = \frac{3}{2.3} sec

     t = 1.3sec

Therefore, the time taken to fill entire length 0f the string is 1.3 sec.

7 0
3 years ago
Why would an orange roll off your cafeteria tray if you stopped suddenly
Leviafan [203]
Because the momentum would still be applied to the orange if the tray stopped moving
3 0
3 years ago
Other questions:
  • ________ occurs when the horizontal winds move air against mountain ranges, forcing air to rise as it passes over the mountains.
    15·1 answer
  • 17. Matthew has a piece of wood with mass of 278 g and a volume of 375 cm^3. What is the wood’s density? a. Step 1: Formula ____
    10·1 answer
  • 7. How much work is done in moving a charge of 10 micro coulombs 1 meter along an equipotential of 10 volts?
    14·2 answers
  • Please help with this science thank you
    11·1 answer
  • Which of the following statements is true?
    8·1 answer
  • An electromagnetic wave travels in a vacuum. The wavelength of the wave is tripled. How is this accomplished?
    9·1 answer
  • what is the position of the earth when the sun rises to its lowest midday position in the sky in the northern hemisphere and the
    8·1 answer
  • A car is traveling at a constant speed of 20 m/s for 3 seconds. Then the driver puts on the brakes. The total distance the car t
    5·1 answer
  • Một vật dao động điều hòa với phương trình x= 4cos(6πt) cm. Kể từ khi vật bắt đầu dao động, thời điểm vật qua a) vị trí cân bằng
    7·1 answer
  • Your English teacher runs 0.80 km north and 1.20 km west. What is the magnitude of the resultant vector of this position?
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!