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riadik2000 [5.3K]

3 years ago

15

Whether or not electrons will be ejected from metal when light shines on the metal depends on

1 answer:

Gemiola [76]3 years ago

3 0

Answer:

Mark me as barinlest

Explanation:

If you shine light of high enough energy on to a metal, electrons will be emitted from the metal. Light below a certain threshold frequency, no matter how intense, will not cause any electrons to be emitted. Light above the threshold frequency, even if it's not very intense, will always cause electrons to be emitted.

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It takes Serina 0.25 hours to drive to school. Her route is 16 km long. What is Serina’s average speed on her drive to school?

tankabanditka [31]

Answer:

17.78 m/s

Explanation:

Average speed is found by simply dividing the distance travelled by the time that it took to finish the trip. It's measured in meters per second (m/s), so first convert the quantities.

1 km = 1000 m, so 16 km is 16000 m

0.25 hours is 15 minutes. Since 1 minute is 60 seconds, then 15 minutes must be 900 seconds.

Thus:

average speed = total distance/total time = 16000 m / 900 s = 17.78 m/s

Hope this helps!

Brainliest please!

5 0

3 years ago

8. A car starts from rest and accelerates at 5.5ms in an easterly direction.

snow_lady [41]

Initial velocity=0m/s=u
Acceleration=a=5.5m/s^2

#8.1

t=12s

$\\ \sf\longmapsto v=u+at$

$\\ \sf\longmapsto v=0+5.5(12)$

$\\ \sf\longmapsto v=66m/s$

#8.2

u=0m/s
v=18m/s
a=5.5m/s^2

Use third equation of kinematics

$\\ \sf\longmapsto v^2-u^2=2as$

$\\ \sf\longmapsto s=\dfrac{v^2-u^2}{2a}$

$\\ \sf\longmapsto s=\dfrac{18^2-0^2}{2(5.5)}$

$\\ \sf\longmapsto s=\dfrac{324}{11}$

$\\ \sf\longmapsto s=29.4m$

8 0

3 years ago

Read 2 more answers

PLEASE HELP SOON

Kitty [74]

Answer:you in connections too?

Explanation:

7 0

4 years ago

Read 2 more answers

On average, both arms and hands together account for 13 % of a person's mass, while the head is 7.0% and the trunk and legs acco

lianna [129]

Answer:

$\dot n_{f} = 85.177\,rpm$

Explanation:

The expression for the moment of inertia of the person is:

Arms outstretched

$I = \frac{1}{12}\cdot (0.13)\cdot (61\,kg)\cdot (1.40\,m)^{2} + \frac{1}{2}\cdot (0.87)\cdot (61\,kg)\cdot (0.35\,m)^{2}$

$I = 4.546\,kg\cdot m^{2}$

Arms parallel to the trunk

$I = \frac{1}{2}\cdot (61\,kg)\cdot (0.35\,m)^{2}$

$I = 3.736\,kg\cdot m^{2}$

The final angular speed is found by means of the Principle of Angular Momentum Conservation:

$I_{o}\cdot \dot n_{o} = I_{f}\cdot \dot n_{f}$

$\dot n_{f} = \frac{I_{o}}{I_{f}}\cdot \dot n_{o}$

$\dot n_{f} = \left(\frac{4.546\,kg\cdot m^{2}}{3.736\,kg\cdot m^{2}}\right)\cdot (70\,rpm)$

$\dot n_{f} = 85.177\,rpm$

8 0

3 years ago

The speed limit on an interstate highway is posted at 75mi/h. What is the speed in kilometers per hour? In feet per second?

Tatiana [17]

Answer:

See explanation

Explanation:

The conversion factor from miles per hour to kilometers per hour is 1.609344.

Hence;

To convert 75mi/h to kilometers per hour,

75mi/h * 1.609344 = 120.7 kilometers per hour

b)

To convert 75mi/h to feet per second

Since

1 mile per hour = 1.46667 foot per second

75mi/h = 75 * 1.46667 = 110 feet per second

5 0

3 years ago