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erica [24]
3 years ago
5

An automobile starts from rest and travels down a straight section of road. The distance s (in feet) of the car from the startin

g position after t seconds is given by s(t)=5t3 (a) Find the instantaneous velocity (in feet per second) at t=4 seconds.
Physics
1 answer:
Vladimir [108]3 years ago
4 0

Answer: 240 ft/sec

Explanation:

If the distance s, of the car regarding his starting position, is defined as a function of time, by definition, the instantaneous velocity at any time, is given by the derivative of the displacement (distance from origin) respect the time, as follows;

v = ds / dt ⇒ v= d/dt (5 t³) = 15 t² = 15 t²

Replacing by t=4 s, we get:

v = 15. 4² = 15.16 = 240 ft/sec

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A high speed train is traveling at a speed of 44.7 m/s when the engineer sounds the 415 Hz warning horn. The speed of sound is 3
il63 [147K]

Answer:

Explanation:

Speed of the source of sound = v = 44.7 m/s

Speed of sound = V = 343 m/s

a) Apparent  frequency as the train approaches = f =  [V /(V -v) ] × f

= [343 / (343 - 44.7) ] × 415  = 477.18 Hz

Wave length =  λ = v / f = 343 / 477.18 = 0.719 m

b) Frequency heard as the train leaves = f ' =  [V / ( V + v) ] f

                                                                     = [343 / { 343 + 44.7 ) ] x 415

                                                                      = 367.2 Hz

Wavelength when leaving = v / f = 343 / 367.2 = 0.934 m

8 0
4 years ago
Which requires more work, lifting a 10.0kg load a vertical distance of 2m or lifting a 5.0kg load a distance of 4m?
Minchanka [31]

For each load,  Work = (mass) x (gravity) x (distance .

Bigger load:      Work = (10 kg) x (9.8 m/s²) x (2 m) = 196 joules .

Smaller load:    Work = (5 kg)  x  (9.8 m/s²)  x  (4 m) = 196 joules.

The work required is equal in both cases.

The mass ratio of  2:1  is exactly balanced by
the height ratio of  1:2 .

6 0
3 years ago
A city of punjab has 15 percemt chance of wet weather on any given day. What is probability that it will take a week for it thre
sesenic [268]

Answer:

The probability that it will take a week for it three wet weather on 3 separate days is 0.06166 and its standard deviation is 0.9447

Explanation:

We are given that A city of Punjab has 15 percent chance of wet weather on any given day.

So, Probability of wet weather = 0.15

Probability of not being a wet weather = 1-0.15 =0.85

We are supposed to find probability that it will take a week for it three wet weather on 3 separate days

Total number of days in a week = 7

We will use binomial over here

n = 7

p =probability of failure = 0.15

q = probability of success=0.85

r=3

Formula :P(r=3)=^nC_r p^r q ^{n-r}

P(r=3)=^{7}C_{3} (0.15)^3 (0.85)^{7-3}\\P(r=3)=\frac{7!}{3!(7-3)!} (0.15)^3 (0.85)^{7-3}\\P(r=3)=0.06166

Standard deviation =\sqrt{n \times p \times q}

Standard deviation =\sqrt{7 \times 0.15 \times 0.85}

Standard deviation =0.9447

Hence The probability that it will take a week for it three wet weather on 3 separate days is 0.06166 and its standard deviation is 0.9447

4 0
3 years ago
A 0.50-kg object moves in a horizontal circular track with a radius of 2.5 m. An external forceof 3.0 N, always tangent to the t
kodGreya [7K]

The work done by the force is 47.1 J

Explanation:

The work done by a force in moving an object is given by

W=Fd cos \theta (1)

where

F is the magnitude of the force

d is the distance covered by the object

\theta is the angle between the direction of the force and the motion of the object

In this problem, the force applied to the object is

F = 3.0 N

This force is always tangential to the track: this means that at every instant, the force is parallel to the motion of the object, so

\theta=0

And the distance covered is equal to the circumference of the circle, which is:

d=2\pi r=2\pi (2.5 m)=15.7 m

where r = 2.5 m is the radius.

Now we can substitute into eq.(1) to find the work done:

W=(3.0)(15.7)(cos 0)=47.1 J

Learn more about work:

brainly.com/question/6763771

brainly.com/question/6443626

#LearnwithBrainly

4 0
3 years ago
Can someone please help me? Will give brainliest.
lora16 [44]
Needs are less than resources, and the population increases.
5 0
4 years ago
Read 2 more answers
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