PHYSICS HIGH SCHOOL

A ball is thrown directly downward with an initial speed of 8.00 m/s, from a height of 30.0 m. After what time interval does it strike the ground?

Answers

Answer 1
Answer: We can use the equation of motion:
s = ut + 1/2 x at²
Both the velocity and acceleration are downwards so we'll consider the downward direction positive
30 = 8t + 4.91t²
4.91t² + 8t - 30 = 0
Solving the quadratic:
t = 1.79 s; t = -3.42 s
Negative time is not possible so second value discarded. Time taken = 1.79 seconds

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Select all that apply.A longitudinal wave is characterized by _____.
peaks compressions dips rarefactions

Answers

A longitudinal wave ischaracterized by rarefactions. A longitudinal wave is a wave motion wherein theparticles in the wave medium are displaced parallel to the advancing wave. When motionis detected from the source, the particle next to it vibrates from its rest positionand a progressive change in phase vibration is observed at each particle withinthat wave. The result is that the energy is transported from one region to theother. These combined motions result in the movement of alternating regions of rarefactionin the direction of transport of energy.       
It's characterized by both compression and rarefaction.

(the compression in front of the waves induces a rarefaction behind the wave)

Help me with this problem please? c:Which appliance uses more energy?

A.) a 30-watt CD player used for 3 hours (10,800 seconds)
B.) a 300-watt blender used for 2 minutes (120 seconds)
C.) a 1,500-watt hair dryer used for 3 minutes (180 seconds)
D.) a 200-watt computer used for 10 hours ( 36,000 seconds)

Answers

30*3*60=5400
300*2=600
1500*3=4500
200*10*60=120000

the computer uses more energy. 
(you can multiply all results by 60 to get the energy in J, but it's not necessary for the comparison)

Answer:

a 200-watt computer used for 10 hours ( 36,000 seconds)

Explanation:

As we move above up from one trophic level to another in an energy pyramid, what happens to the energy?a. It decreases from one trophic level to another.
b. It remains the same for each trophic level.
c. It increases from one trophic level to another.

Answers

As we move above up from one trophic level to another in an energy pyramid, what happens to the energy?

a. It decreases from one trophic level to another.
b. It remains the same for each trophic level.
c. It increases from one trophic level to another.

As we move above up from one trophic level to another in an energy pyramid, the energy level decreases from one trophic level to another. The answer is letter A.

An elevator weighing 6,000 N moves up a distance of 10.0 meters in 30.0 seconds. a. How much work did the elevator’s motor do? b. What was the power of the elevator’s motor in watt and in horsepower?

Answers

Assume that work is equal to force x distance or w=fd. The force here is 6,000n and distance is 10.0 so therefore w=(6000n)(10.0m) and use that to do p=wt (power = work x time

Which of the following is an SI base unit for measuring mass?Ampere
Gram
Meter
Pound

Answers

Among the option given below, the most appropriate SI base unit for measuring mass is Gram. Thus, the correct option is B.

What is an SI unit?

An SI unit may be defined as a form of the metric system that is utilized universally as a standard for measurements. It is an international system of units. The expanded form of the SI unit is Systeme International.

The exact SI base unit for measuring mass is the kilogram, kg. But it is not mentioned in the options. So, the most appropriate SI base unit for measuring mass is Gram.

Ampere is the SI base unit for measuring the electric current. A Meter (m) is the SI base unit for measuring length. A Pound is the international standard symbol used as a unit of mass and i.e. lb.

Therefore, among the option given below, the most appropriate SI base unit for measuring mass is Gram. Thus, the correct option is B.

To learn more about SI units, refer to the link:

brainly.com/question/16393390

#SPJ5
From that list, the only unit of mass is the "gram". 
But that isn't the SI base unit of mass. 
The base unit is the kilogram.

The cloud of interstellar dust and gas that forms a star is known as aA. white dwarf.
B. protostar.
C. red giant.
D. nebula.

Answers

D. nebula

Nebula is the cloud of interstellar dust and gas that forms a star. It is collborately shaped during colliding and collapsing of the interstellar mediums this is influenced by the gravitational attraction of the atoms and particles in the entites. Hence, there are three types of nebular namely, are classical nebula, diffuse nebula, planetary nebular and supernova remnants.
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