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
OlgaM077 [116]
3 years ago
7

A 2,000-kilogram car uses a braking force of 12,000 Newton to stop in 5 seconds. What is its initial speed of the car?

Physics
2 answers:
AnnZ [28]3 years ago
5 0
First, solve for the acceleration of the car. You know the mass of the car and the braking force, so you can use the equation Force = Mass x Acceleration. This gives you 12,000 = 2,000 x A. Divide 12,000 by 2,000 to find the acceleration equal to 6 m/s^2. This is the rate that the car is slowing down at. Velocity is equal to accleration x time (rate x time), so you multiply 6 by the time of 5 seconds. This leaves you with a velocity of 30 m/s or about 67.1 mph.
jeka943 years ago
3 0

<u>Answer:</u> The initial speed of the car is 30 m/s

<u>Explanation:</u>

Force is defined as the push or pull on an object with some mass that causes change in its velocity.

It is also defined as the mass multiplied by the acceleration of the object.

Mathematically,

F=m\times a

where,

F = force exerted on the car = 12,000 N

m = mass of the car = 2,000 kg

a = acceleration of the car = ?

Putting values in above equation, we get:

12000kg.m/s^2=2000kg\times a\\\\a=\frac{12000}{2000}=6m/s^2

  • To calculate the initial speed of the car, we use first equation of motion:

v=u+at

where,

v = final speed of the car = 0 m/s   (brakes are applied)

u = initial speed of the car = ?

a = acceleration of the car = -6m/s^2   (as the car is getting stopped)

t = time taken = 5 sec

Putting values in above equation, we get:

0=u+(-6\times 5)\\\\u=0+30\\\\u=30m/s

Hence, the initial speed of the car is 30 m/s

You might be interested in
A train whistle is heard at 300 Hz as the train approaches town. The train cuts its speed in half as it nears the station, and t
spin [16.1K]

Answer:

The speed of the train before and after slowing down is 22.12 m/s and 11.06 m/s, respectively.

Explanation:

We can calculate the speed of the train using the Doppler equation:

f = f_{0}\frac{v + v_{o}}{v - v_{s}}        

Where:

f₀: is the emitted frequency

f: is the frequency heard by the observer  

v: is the speed of the sound = 343 m/s

v_{o}: is the speed of the observer = 0 (it is heard in the town)

v_{s}: is the speed of the source =?

The frequency of the train before slowing down is given by:

f_{b} = f_{0}\frac{v}{v - v_{s_{b}}}  (1)                  

Now, the frequency of the train after slowing down is:

f_{a} = f_{0}\frac{v}{v - v_{s_{a}}}   (2)  

Dividing equation (1) by (2) we have:

\frac{f_{b}}{f_{a}} = \frac{f_{0}\frac{v}{v - v_{s_{b}}}}{f_{0}\frac{v}{v - v_{s_{a}}}}

\frac{f_{b}}{f_{a}} = \frac{v - v_{s_{a}}}{v - v_{s_{b}}}   (3)  

Also, we know that the speed of the train when it is slowing down is half the initial speed so:

v_{s_{b}} = 2v_{s_{a}}     (4)

Now, by entering equation (4) into (3) we have:

\frac{f_{b}}{f_{a}} = \frac{v - v_{s_{a}}}{v - 2v_{s_{a}}}  

\frac{300 Hz}{290 Hz} = \frac{343 m/s - v_{s_{a}}}{343 m/s - 2v_{s_{a}}}

By solving the above equation for v_{s_{a}} we can find the speed of the train after slowing down:

v_{s_{a}} = 11.06 m/s

Finally, the speed of the train before slowing down is:

v_{s_{b}} = 11.06 m/s*2 = 22.12 m/s

Therefore, the speed of the train before and after slowing down is 22.12 m/s and 11.06 m/s, respectively.                        

I hope it helps you!                                                        

7 0
2 years ago
A traditional unit of length in Japan is the ken (1ken =1.97 m) . What are the ratios of (a) square kens to a square meters? and
Law Incorporation [45]
4 . I hope I helped your welcome
6 0
3 years ago
Science is the process of asking scientific questions about which of the following?
Eva8 [605]

the answer to your question would be D.

4 0
3 years ago
Read 2 more answers
Newton’s third law of motion describes A. action and reaction forces. B. balanced forces. C. centripetal forces. D. net force.
IgorC [24]
<span>A. action and reaction forces.</span>
6 0
3 years ago
Read 2 more answers
Momentum quiz for physics
jek_recluse [69]

Answer:

p=mv=(813kg)(17)= 13,821 kg m\s

7 0
3 years ago
Other questions:
  • An electron is emmited by an atomic nucleus in the process of...
    11·2 answers
  • the field of meteorology is based on studying which of the following? a.)stars and plants b.) weather and climate c.)rocks and m
    9·1 answer
  • Which of the following statements is true about scientific theories?
    11·1 answer
  • Four equal negative point charges are located at the corners of a square, their positions in the xy-plane being (1,1), (−1,1), (
    14·2 answers
  • How does beam spreading affect the temperature on earth and the seasons
    13·1 answer
  • The variable you want to test is...
    6·1 answer
  • Leandra is baking cookies , and they are ready to come out of the oven . Before she takes them out of the oven , she puts her mi
    5·1 answer
  • Why is deforestation a serious global environment problem
    5·1 answer
  • Can someone awnser this
    14·1 answer
  • A standard baseball has a circumference of apoximately 23cm. If a baseball had the same mass per unit volume as a neutron or a p
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!