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3 years ago

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The atomic number of yttrium is 39. The atomic mass of one of its isotopes is 89. How many neutrons are in an atom of this isoto

pe?

1 answer:

gogolik [260]3 years ago

8 0

50. The atomic mass is essentially a tally of all of the atoms in the nucleus, since electrons are essentially negligible in mass.

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A train accelerates from 30 km/h to 45 km/h in 15.0 second. Find its acceleration and the distance it travels during this time

Bad White [126]

Answer:

a. Acceleration, a = 0.28 m/s²

b. Distance, S = 156 meters

Explanation:

Given the following data;

Initial velocity = 30 km/h

Final velocity = 45 km/h

Time = 15 seconds

a. To find the acceleration;

Conversion:

30 km/h to m/s = 30*1000/3600 = 8.33 m/s

45 km/h to m/s = 45*1000/3600 = 12.5 m/s

Mathematically, acceleration is given by the equation;

$Acceleration (a) = \frac{final \; velocity - initial \; velocity}{time}$

Substituting into the equation;

$a = \frac{12.5 - 8.3}{15}$

$a = \frac{4.2}{15}$

Acceleration, a = 0.28 m/s²

b. To find the distance travelled, we would use the second equation of motion given by the formula;

$S = ut + \frac {1}{2}at^{2}$

Where;

S represents the displacement or height measured in meters.

u represents the initial velocity measured in meters per seconds.

t represents the time measured in seconds.

a represents acceleration measured in meters per seconds square.

Substituting into the equation, we have;

$S = 8.3*15 + \frac {1}{2}*(0.28)*15^{2}$

$S = 124.5 + 0.14*225$

$S = 124.5 + 31.5$

S = 156 meters

8 0

3 years ago

How the forces makes effect on the state of motion of an object ? <br><br> Plz ans fast urgent

Ksju [112]

Answer:

1. It may change the direction of an object in motion.

2. It may cause change in velocity of an object in motion.

Explanation:

1.It may change the direction of an object in motion.

When an object is in motion,an applied force on that object may change its direction.

For example, a sailboat moving eastward, can suddenly change its direction by interaction of a storm wind blowing form the south.

2. It may cause change in velocity of an object in motion .

A force applied to an object in motion can increase or decrease its speed. When the force is applied to the object in motion in the direction of that object, its velocity may increase.

On the other hand, when the force is applied in the opposite direction to the object in motion, its velocity may reduce.

6 0

3 years ago

A cylinder contains a mixture of helium and argon gas in equilibrium at 160°C.

Artist 52 [7]

Answer:

a. E=8.97*10^{-21} J

b. v-He2 = 1.161 km/s

v-Ar2 = 369.74 m/s

Explanation:

(a) The average kinetic energy is given by

$E_k=\frac{1}{2}k_BT$

where KB is the Boltzman's constant and T is the temperature. For each molecule we have:

$E_k=\frac{3}{2}(1.38066*10^{-23}\frac{J}{K})(433.15K)=8.97*10^{-21}J$

is the same for both type of molecules because is independent of the mass

(b)

$v_{rms}=\sqrt{\frac{3RT}{M}}$

where R is the constant of ideal gases, and M is the mass of the molecule. BY replacing for each type of molecule we obtain:

$v_{rms-He_{2}}=\sqrt{\frac{3(8.311434Jmol^{-1}K^{-1})(433.15K)}{0.008kg\ mol^{-1}}}=1161.9\frac{m}{s}\\\\v_{rms-Ar_{2}}=\sqrt{\frac{3(8.311434Jmol^{-1}K^{-1})(433.15K)}{0.079kg\ mol^{-1}}}=369.74\frac{m}{s}$

v-He2 = 1.161 km/s

v-Ar2 = 369.74 m/s

hope this helps!!

8 0

3 years ago

A runner is jogging in a straight line at a steady Vr= 3.4km/hr. When the runner is L=8km from the finish line, a bird begins fl

Lynna [10]

Answer:

The cumulative distance that the bird travel is 13.33 Km

Explanation:

Given that,

Velocity of runner = 3.4 km/hr

Distance = 8 km

Velocity of bird = 17 km/hr

Let x is the distance from the origin where the runner run into the bird

We need to calculate the value of x

Using time of runner and bird

$t_{r}=t_{b}$

$\dfrac{d_{r}}{v_{r}}=\dfrac{d_{b}}{v_{b}}$

Put the value into the formula

$\dfrac{x}{3.4}=\dfrac{8+(8-x)}{17}$

$17x=3.4\times8+3.4(8-x)$

$17x=27.2+27.2-3.4x$

$17x+3.4x=54.4$

$x=\dfrac{54.4}{20.4}$

$x=2.67$

We need to calculate the cumulative distance that the bird travel

Using distance of bird

$d_{b}=16-x$

Put the value into the formula

$d_{b}=16-2.67$

$d_{b}=13.33\ km$

Hence, The cumulative distance that the bird travel is 13.33 Km

7 0

3 years ago

When drawing a free-body diagram for an object on an inclined surface, which way does the force of gravity point? A. Straight do

babunello [35]

A- Straight Down

Remember wherever the object is, whether it is straight or inclined, gravitational pull will always act downwards.

8 0

4 years ago