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
adell [148]
3 years ago
6

An Olympic track runner starts from rest and has an acceleration of 2.4 m/s2 for 3.6 s, then has zero acceleration for the remai

nder of the race. Find the runner's speed (in m/s) at the following times.
Physics
1 answer:
rjkz [21]3 years ago
5 0

Answer:

The runner's speed at the following times would remain 8.64 m/s.

Explanation:

Acceleration definition: Acceleration is rate of change in velocity of an object with respect to time.

In this case, after 3.6 seconds the acceleration is zero, it means that the velocity of the runner after 3.6 seconds is not changing and it will remain constant for the remainder of the race. Now, we have to find the velocity of the runner that he had after 3.6 seconds and that would be the runner's speed for the remainder of the race. For this we use first equation of motion.

First equation of motion:        Vf = Vi + a×t

Vf stands for final velocity

Vi stands for initial velocity

a stands for acceleration

t stands for time

In the question, it is mentioned that the runner starts from rest so its initial velocity (Vi) will be 0 m/s.

The acceleration (a) is given as 2.4 m/s²

The time (t) is given as 3.6 s

Now put the values of Vi, a and t in first equation of motion

                       Vf = Vi + a×t

                       Vf = 0 + 2.4×3.6

                       Vf = 2.4×3.6

                       Vf = 8.64 m/s

So,the runner's speed at the following times would remain 8.64 m/s.

You might be interested in
A person is riding a bicycle, and its wheels have an angular velocity of 10.7 rad/s. Then, the brakes are applied and the bike i
Scilla [17]

Answer:

(a) t = 22.9 s

(b) α= - 0.467 rad/s²

Explanation:

The uniformly accelerated circular movement, is a circular path movement in which the angular acceleration is constant.

We apply the equations of circular motion uniformly accelerated :

ωf ²=  ω₀² + 2*α*θ  Formula (1)

ωf= ω₀ + α*t Formula (2)

Where:

θ : angle that the body has rotated in a given time interval (rad)

α : angular acceleration (rad/s²)

t : time interval (s)

ω₀ : initial angular speed ( rad/s)

ωf : final angular speed ( rad/s)

Data

θ =  19.5 revolutions  : angular displacement of each wheel or angle that the  wheel has rotated in a given time interval

ω₀= 10.7 rad/s :  initial angular speed of the Wheel ( rad/s)

ωf = 0 : final angular speed  of the Whee( rad/s)

Calculating of the angular acceleration (α )

We replace data in the fómula (1),considering that 1 revolution is equal to 2π radians :

ωf ²=  ω₀² + 2*α*θ

(0 )²=  (10.7)² + 2*α*(19.5*2*π )

0= 114.49 + (245.04)*α

-114.49 =  (245.04)*α

α= (-114.49) /(245.04)

α= -114.49 /(245.04)

α= -0.467 rad/s²

Time does it take for the bike to come to rest

We replace data in the formula (2)

ωf = ω₀ + α*t

0 =  10.7 + -0.467*t

-10.7  = - 0.467*t    we multiply by (-1) both sides of the equation :

10.7  = 0.467*t  

t = 10.7 / 0.467

t = 22.9 s

3 0
3 years ago
I've had several mental breakdowns please help me
sesenic [268]

Answer:

The efficiency of the system is 63.7 %

Explanation:

Given;

input power of the motor, = 1.5 kW = 1,500 W

mass of the car lifted, m = 1300 kg

height through which the car was lifted, h = 1.8 m

time, t = 24 s

The output power of the motor is calculated as;

Output Power = F x v

                        = (mg)  x (d/t)

                        = (1300 x 9.8) x (1.8 / 24)

                        = 12,740 x 0.075

                        = 955.5 W

The efficiency of the system is calculated as;

E = \frac{0utput \ power}{1nput \ power} \times \ 100\%\\\\E = \frac{955.5}{1500} \times \ 100\% \\\\E = 63.7 \ \%

The correct answer is 63.7%

4 0
3 years ago
A 4kg rock isn’t rolling 10m/s. Find it’s kinetic energy.
scoundrel [369]

Kinetic energy = (1/2) (mass) (speed)²

The rock's kinetic energy is not 

                           (1/2) (4 kg) (10 m/s)²

                      =   (1/2) (4 kg) (100 m²/s²)

                      =         200 Joules .

It may be more, or it may be less.  The only thing
we can be sure of is that it is not 200 Joules.
3 0
3 years ago
Which of the following statements is true?
Bad White [126]
The answer is c hope this helps



6 0
3 years ago
Read 2 more answers
A dog runs east for 21.25 meters. it takes the dog 8.5 seconds to cover this distance. what is the dog's average velocity?
Aleonysh [2.5K]
Velocity=21.25/8.5
= 2.5m/s
answers is b
6 0
3 years ago
Other questions:
  • A football player at practice pushes a 60 kg blocking sled across the field at a constant speed. The coefficient of kinetic fric
    8·2 answers
  • Give me three examples of fossil fuel-based energy sources pls
    11·1 answer
  • Hi, does anyone know the answer for question 2 or 3? Thank you
    8·1 answer
  • A speed boat travels from the dock to the first buoy a distance of 20 meters in 18 seconds it began the trip at a speed of 0 m/s
    15·1 answer
  • Farmers during the dust bowl of the 1930s watched their soil be carried away by wind what process removed the soil from the plac
    13·2 answers
  • When should you use a piece of pipe as a leverage extension on the handle on a wrench?
    5·1 answer
  • Coherent light with wavelength 460 nm falls on a pair of slits. On a screen 1.86 m away, the distance between dark fringes is 3.
    6·1 answer
  • The human ear is most sensitive to the sounds in what range?
    14·1 answer
  • B. A car is moving 4.0 m/s to the right. The car begins to accelerate at a rate of 1.5 m/s/s, to the right. After
    10·1 answer
  • It would not be economical to connect the houses to the National Grid.Give one reason why.
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!