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
guajiro [1.7K]
3 years ago
13

In a race, Usain Bolt accelerates at

Physics
1 answer:
jeka943 years ago
3 0

Answer:

65.87 s

Explanation:

For the first time,

Applying

v² = u²+2as.............. Equation 1

Where v = final velocity, u = initial velocity, a = acceleration, s = distance

From the question,

Given:  u = 0 m/s (from rest), a = 1.99 m/s², s = 60 m

Substitute these values into equation 1

v² = 0²+2(1.99)(60)

v² = 238.8

v = √238.8

v = 15.45 m/s

Therefore, time taken for the first 60 m is

t = (v-u)/a............ Equation 2

t = (15.45-0)/1.99

t = 7.77 s

For the final 40 meter,

t = (v-u)/a

Given: v = 0 m/s(decelerates), u = 15.45 m/s, a = -0.266 m/s²

Substitute into the equation above

t = (0-15.45)/-0.266

t = 58.1 seconds

Hence total time taken to cover the distance

T = 7.77+58.1

T = 65.87 s

You might be interested in
A university is planning to send an optical telescope into orbit. stuents attending the university will be able to view which of
kodGreya [7K]
Where are the answers? If there's anything about a white light coming from space I would choose that one. 
3 0
3 years ago
Read 2 more answers
A veritical brass rod of circular section is loaded by placing a 10 kg wt on top of it .if it's length is 1 m. it's radius of cr
Inga [223]

Answer:

4.37 * 10^-4 J

Explanation:

Energy stored :

mgΔl / 2

m = mass = 10kg ; g = 9.8m/s² ; r = cross sectional Radius = 1cm = 1 * 10-2 m

Δl = mgl / πr²Y

Y = Youngs modulus = Y=3.5 ×10^10 ; l = Length = 1m

Δl = (10 * 9.8 * 1) / π * (1 * 10^-2)²* 3.5 ×10^10

Δl = 98 / 3.5 * π * 10^6

Δl = 0.00000891267

Energy stored :

mgΔl / 2

(10 * 9.8 * 0.00000891267) / 2

= 0.00043672083 J

4.37 * 10^-4 J

3 0
2 years ago
72.0-kg person pushes on a small doorknob with a force of 5.00 N perpendicular to the surface of the door. The doorknob is locat
expeople1 [14]

Answer:I=2 kg-m^2

Explanation:

Given

mass m=72 kg

Force F=5 N

door knob is located at a distance of r=0.8 m from axis

Angular acceleration of door \alpha =2 rad/s^2

Torque T=I\alpha =F\times r

where I=moment of inertia

5\times 0.8=I\times 2

I=2 kg-m^2

4 0
4 years ago
Show that the optimal launch angle for a projectile subject to gravity is 45o by carrying out the following steps: 6. Write down
Lorico [155]

Answer:

sin  2θ = 1    θ=45

Explanation:

They ask us to prove that the optimal launch angle is 45º, for this by reviewing the parabolic launch equations we have the scope equation

            R = Vo² sin 2θ / g

Where R is the horizontal range, Vo is the initial velocity, g the acceleration of gravity and θ the launch angle. From this equation we see that the sine function is maximum 2θ = 90 since sin 90 = 1 which implies that θ = 45º; This proves that this is the optimum angle to have the maximum range.

We calculate the distance traveled for different angle

          R = vo² Sin (2 15) /9.8

          R = Vo² 0.051 m

In the table are all values ​​in two ways

Angle (θ)                  distance R (x)

 0                 0                     0

15                 0.051 Vo²        0.5 Vo²/g

30                0.088 vo²        0.866   Vo²/g

45                0.102 Vo²        1   Vo²/g

60                0.088 Vo²      0.866   Vo²/g

75                0.051 vo²        0.5   Vo²/g

90                0                     0

See graphic ( R Vs θ)  in the attached ¡, it can be done with any program, for example EXCEL

6 0
3 years ago
A person is listening to a tone of 500 Hz sitting from a distance of 450 m from the source of the sound. What is the time interv
VladimirAG [237]

Answer:

ΔX = λ = 0.68 m

Explanation:

Wave speed is related to wavelength and frequency by the equation

          v = λ f

where the speed of sound is 340 m / s

          λ = v / f

          λ = 340/500

          λ = 0.68 m

this is the wavelength, it is the minimum distance for which the wave epitates its movement, which is equal to the distance between two consecutive compressions of the sound

          ΔX = λ = 0.68 m

5 0
3 years ago
Other questions:
  • For a certain spring, k = 15N/m. A weight is hung from the spring, stretching it from 0.3m to 0.4m. What force did the weight pr
    6·1 answer
  • Which is the correct formula for finding the frequency of an electromagnetic wave? f = c – f = f = + c f =
    16·1 answer
  • Which method is used to assign weights to various features of a system?
    7·1 answer
  • A computer draws a current of 10 amperes when plugged into a 220 volt socket. How much power does the computer have?
    12·1 answer
  • What two simple machines make up an axe?
    11·1 answer
  • A train rolls to a stop along a horizontal track without the conductor applying the brakes. What answer choice BEST explains why
    9·1 answer
  • suppose two masses are connected by a spring. compute the formula for the trajectory of the center of mass of the two mass oscil
    15·1 answer
  • An echo is not heard in a small room.why ? give reason<br>​
    8·2 answers
  • Physics part 1 <br><br> I need help answering these
    6·1 answer
  • A 2. 0 kg-book is at rest on a 30 o inclined plane. The normal force acting on the book by the inclined plane is most nearly
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!