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irakobra [83]
2 years ago
5

If a car travels 30.0 mi. north for 30.0 min., 50.0 mi. east for 1.00 hour, and 30.0 mi. south for 30.0 min., what is the averag

e speed of the car over the total trip? 55 mph 55.0 mph 60.0 mph 60. mph
Physics
1 answer:
san4es73 [151]2 years ago
4 0
Note that Speed = Distance/Time.

1st trip:
Distance = 30 mi
Time = 30 min = 0.5 h
Speed = 30/0.5 = 60 mi/h

2nd trip:
Distance = 50 mi
Time = 1 hour
Speed = 50 mi/h

3rd trip:
Distance = 30 mi
Time = 30 min = 0.5 h
Speed = 30/0.5 = 60 mi/h

Average speed = (60 + 50 + 60)/3 = 56.7 mph
The closestanswer is 55 mph

Answer: 55 mph

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SashulF [63]

Answer:

<em>The athlete will rise 1.10 meters off the ground</em>

Explanation:

<u>Vertical Motion</u>

If an object is launched vertically upwards at an initial speed vo, then it will reach a maximum height given by

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\displaystyle a=\frac{F_n}{m}=\frac{2W}{m}=2g

The speed at the end of his push can be computed by

v^2=2ay

Replacing the value of a obtained above:

v^2=4gy

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v^2=4\cdot 9.8\cdot 0.55

v=4.64\ m/s

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\displaystyle y_m=\frac{4.64^2}{2\cdot 9.8}

y_m=1.10\ m

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2 years ago
A helicopter pulls upward by means of a rope on a 250 kg crate to lift it UNIFORMLY. What is the net force on the crate?
Cloud [144]

Answer:

The net force = 0

Explanation:

The given information includes;

The mass of the crate = 250 kg

The way the helicopter lifts the crate = Uniformly (constant rate (speed), no acceleration)

In order to pull the crate upwards, the helicopter has to provide a force equivalent to the weight of the crate keeping the helicopter on the ground.

The weight of the crate = The mass of the crate × The acceleration due gravity acting on the crate

The weight of the crate, F_w↓ = 250 kg × 9.81 m/s² = 2,452.5 N

The force the helicopter should provide to just lift the crate, F_{(helicopter)}↑ = The weight of the crate = 2,452.5 N

The net force, F_{(net)} = F_{(helicopter)}↑ - F_w↓ = 2,452.5 N - 2,452.5 N = 0

The net force = 0.

3 0
2 years ago
If the distance between us and a star is doubled, with everything else remaining the same, the luminosity Group of answer choice
Savatey [412]

Answer:

remains the same, but the apparent brightness is decreased by a factor of four.

Explanation:

A star is a giant astronomical or celestial object that is comprised of a luminous sphere of plasma, binded together by its own gravitational force.

It is typically made up of two (2) main hot gas, Hydrogen (H) and Helium (He).

The luminosity of a star refers to the total amount of light radiated by the star per second and it is measured in watts (w).

The apparent brightness of a star is a measure of the rate at which radiated energy from a star reaches an observer on Earth per square meter per second.

The apparent brightness of a star is measured in watts per square meter.

If the distance between us (humans) and a star is doubled, with everything else remaining the same, the luminosity remains the same, but the apparent brightness is decreased by a factor of four (4).

Some of the examples of stars are;

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8 0
2 years ago
In a photoelectric effect experiment, electromagnetic radiation containing a finite distribution of wavelengths shines on a meta
Sonja [21]

Answer with Explanation:

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We know that  

f=\frac{v}{\lambda}

Frequency is inversely proportional to the wavelength.

Therefore, the frequency decrease .

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When energy decreases then the number of photo-electrons emitted by the metal decreases.

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2 years ago
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Answer:

The efficiency of each cycle of a heat engine is 30 %.                                                            

Explanation:

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We need to find the efficiency of each cycle. The efficiency of heat engine is defined as the ratio of work output to the energy supplied. It is given by :

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\eta=0.3

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\eta=30\%

So, the efficiency of each cycle of a heat engine is 30 %. Hence, this is the required solution.

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2 years ago
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