An open system starts with 52 J of mechanical energy. The energy changes

Strontium−90 is one of the products of the fission of uranium−235. This strontium isotope is radioactive, with a half-life of 28

Ludmilka [50]

Answer : The time passed in years is 20.7 years.

Explanation :

Half-life = 28.1 years

First we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{28.1\text{ years}}$

$k=2.47\times 10^{-2}\text{ years}^{-1}$

Now we have to calculate the time passed.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $2.47\times 10^{-2}\text{ years}^{-1}$

t = time passed by the sample = ?

a = initial amount of the reactant = 1.00 g

a - x = amount left after decay process = 0.600 g

Now put all the given values in above equation, we get

$t=\frac{2.303}{2.47\times 10^{-2}}\log\frac{1.00}{0.600}$

$t=20.7\text{ years}$

Therefore, the time passed in years is 20.7 years.

8 0

3 years ago

Compare and contrast the health benefits and the amount of physical or mental energy needed between active leisure activities an

dolphi86 [110]

This is the answer "Some active leisure activities, such as yoga and running, require a great deal of physical energy, while other activities, like playing chess, require a substantial amount of mental energy. Passive leisure activities, such as watching TV or going to the movies, require little to no physical or mental energy. Because of the exertion of physical or mental energy, active leisure activities have more health benefits than passive leisure activities." hope it help you?:)

4 0

2 years ago

A horizontal 745 N merry-go-round of radius

Arturiano [62]

Answer:

The kinetic energy of the merry-goround after 3.62 s is 544J

Explanation:

Given :

Weight w = 745 N

Radius r = 1.45 m

Force = 56.3 N

To Find:

The kinetic energy of the merry-go round after 3.62 = ?

Solution:

Step 1: Finding the Mass of merry-go-round

$m = \frac{ weight}{g}$

$m = \frac{745}{9.81 }$

m = 76.02 kg

Step 2: Finding the Moment of Inertia of solid cylinder

Moment of Inertia of solid cylinder I = $0.5 \times m \times r^2$

Substituting the values

Moment of Inertia of solid cylinder I

=> $0.5 \times 76.02 \times (1.45)^2$

=> $0.5 \times 76.02\times 2.1025$

=> $79.91 kg.m^2$

Step 3: Finding the Torque applied T

Torque applied T = $F \times r$

Substituting the values

T = $56.3 \times 1.45$

T = 81.635 N.m

Step 4: Finding the Angular acceleration

Angular acceleration , $\alpha = \frac{Torque}{Inertia}$

Substituting the values,

$\alpha = \frac{81.635}{79.91}$

$\alpha = 1.021 rad/s^2$

Step 4: Finding the Final angular velocity

Final angular velocity , $\omega = \alpha \times t$

Substituting the values,

$\omega = 1.021 \times 3.62$

$\omega = 3.69 rad/s$

Now KE (100% rotational) after 3.62s is:

KE = $0.5 \times I \times \omega^2$

KE = $0.5 \times 79.91 \times 3.69^2$

KE = 544J

6 0

3 years ago

Explain the Construction of the mercury barometer

boyakko [2]

Answer:

The basic construction, unchanged since Torricelli's experiment in 1643, is a glass tube about three feet long, closed at one end, filled with mercury, and inverted with the open end immersed in a cistern of mercury.

6 0

2 years ago

Which object has the least thermal energy?

hichkok12 [17]

Answer:

2kg brick

Explanation:

2kg brick at 25 degrees.

5 0

2 years ago

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