Mathematics, 29.08.2020 01:01 diamonds5307

An object dropped from the top of a tall building falls y = 4.9t^2 meters in the first t seconds. What is the object’s average speed during the first 4 seconds? A.) 4.9 m/s
B.) 9.8 m/s
C.) 19.6 m/s
D.) 39.2 m/s
E.) 78.4 m/s

What is the objects instantaneous speed at t=4 seconds?
A.) 4.9 m/s
B.) 9.8 m/s
C.) 19.6 m/s
D.) 39.2 m/s
E.) 78.4 m/s

Answers: 3

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Answers

Answer from: theoriginalstal4234

Average Speed

C.) 19.6 m/s

Instantaneous Speed

D.) 39.2 m/s

Step-by-step explanation:

Given the function to represent the distance traveled by the object in seconds:

y = 4.9t^2

To find:

Object's average speed during the first 4 seconds ?

Instantaneous speed at t = 4 seconds

Solution:

Average speed of a moving object is given by, Total Distance covered divided by Total time taken.

$\text{Average Speed = }\dfrac{\text{Total Distance traveled}}{\text{Total Time Taken}}$

Let us find the distance traveled in 4 seconds by putting t = 4 in the equation y = 4.9t^2

$y = 4.9\times 4^2 = 78.4\ m$

Now, let us put the values in the formula:

$\text{Average Speed = }\dfrac{78.4}{4} = \bold{19.6\ m/s}$

For instantaneous speed, we need to differentiate y w.r.to t:

$Speed = \dfrac{d}{dt}y = 4 \times 4.9 t^{2-1}\\\Rightarrow Speed = \dfrac{d}{dt}y = 4 \times 4.9 t$

Now, let us put t = 4 seconds

Speed = $4\times 4.9\times 4$ = 39.2 m/s

The answers are:

Average Speed

C.) 19.6 m/s

Instantaneous Speed

D.) 39.2 m/s

Answer from: Quest

answer:

payment just for service

→

87.12

payment for service including tax

→

94.09

explanation:

service only with 20% tip

→

72.6

(

100

)

87.12

in the opening of the question the word 'service' is associated only with the pretax value.

the closing part of the question asks: how much did she pay for the

service

−−−−−−

so technically the answer is

→

72.6

(

100

)

87.12

however, the intention of the question provider may have been that your answer is to be

87.12

(

100

)

94.09

to 2 decimal places.

payment just for service

→

87.12

payment for service including tax

→

94.09

tony b

mar 21, 2017

answer:

trying to explain it another way

explanation:

service charge

→

72.60

20% tip

100

72.60

14.52

−−−−−−

←

add

87.12

tax

100

87.12

6.97

−−−−−

←

add

94.09

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An object dropped from the top of a tall building falls y = 4.9t^2 meters in the first t seconds. Wh...

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