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3 years ago

46 points :)

Physics

2 answers:

azamat3 years ago

5 0

Answer:

Amount of material that has not decayed

Explanation:

Just took the test on ed2020

IgorC [24]3 years ago

3 0

Answer:

Its is dividing by 2

Explanation:

It starts with 100 them it goes to 50, 25, 12.5 so its a cycle of dividing by 2

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a child riding a bicycle at 15 meters per second accelerates at -3,0 meters per second? for 4.0 seconds. What is the child's spe

Vika [28.1K]

Answer:

Explanation:

Given data

initital velocity u=15m/s

deceleration a=3m/s^2

time t= 4 seconds

final velocity v= ?

Applying the expression

v=u+at------1

substituting our data into the expression we have

v=15+3*4

v=15+12

v=27m/s

The velocity after 4 seconds is 27m/s

5 0

3 years ago

You then measure Polly's internal temperature to be 13oC, which is quite a drop from the normal human body temperature of 37oC.

ankoles [38]

Answer:

The specific heat is 3.47222 J/kg°C.

Explanation:

Given that,

Temperature = 13°C

Temperature = 37°C

Mass = 60 Kg

Energy = 5000 J

We need to calculate the specific heat

Using formula of energy

$Q= mc\Delta T$

$c =\dfrac{Q}{m\Delta T}$

Put the value into the formula

$c=\dfrac{5000}{60\times(37-13)}$

$c=3.47222\ J/kg^{\circ}C$

Hence, The specific heat is 3.47222 J/kg°C.

5 0

3 years ago

The brakes on your automobile are capable of creating a deceleration of 4.6 m/s^2. If you are going 114 km/h and suddenly see a

drek231 [11]

Answer:

The minimum time to get the car under max. speed limit of 79 km/h is 2.11 seconds.

Explanation:

$a=\frac{V_f-V_0}{t}$

isolating "t" from this equation:

$t=\frac{V_f-V_0}{a}$

Where:

a= $-4.6m/s^2$ (negative because is decelerating)

$V_f= 79 km/h$

$V_0= 114 km/h$

First we must convert velocity from km/h to m/s to be consistent with units.

$79\frac{km}{h}*\frac{1000m}{1 km}*\frac{1h}{3600s}=\frac{79*1000}{3600}=21.94 m/s$

$114\frac{km}{h}*\frac{1000m}{1 km}*\frac{1h}{3600s}=\frac{114*1000}{3600}=31.67 m/s$

So;

$t=\frac{V_f-V_0}{a}=\frac{21.94 m/s-31.66m/s}{-4.6 m/s^2}=2.11 s$

7 0

3 years ago

To form a better telescope, you can interchange eyepieces for new focal lengths. A new design lets you replace both lenses, whic

HACTEHA [7]

Answer:

option (b)

Explanation:

for a telescope, the object is placed very far from the objective lens so the focal length of objective is large and the eye piece is of short focal length.

So, long focal length objective and short focal length eyepiece.

Option (b) is correct.

8 0

3 years ago

Two Carnot air conditioners, A and B, are removing heat from different rooms. The outside temperature is the same for both rooms

lakkis [162]

Answer:

(a) 333.77 J

(b) 237.85 J

(d) 4667.85 J

Explanation:

Temperature of source, TH = 314 K

Temperature of A, Tc = 292 K

Temperature of B, Tc' = 298 K

heat taken out, Qc = 4430 J

Let the heat deposited outside is QH and QH' by A and B respectively.

$\frac{Q_H}{Q_c}=\frac{T_H}{T_c}\\\\Q_H = \frac{4430\times314}{292}=4763.77 J$

Now

$\frac{Q_H'}{Q_c}=\frac{T_H}{T_c'}\\\\Q_H' = \frac{4430\times314}{298}=4667.85 J$

(a) Work done for A

W = QH - QC = 4763.77 - 4430 = 333.77 J

(b) Work done for B

W' = QH' - Qc = 4667.85 - 4430 = 237.85 J

(d) QH' = 4667.85 J

4 0

3 years ago