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Svetach [21]
2 years ago
7

The launching velocity of a missile is 20.0 m/s, and it is shot at 53º above the horizontal. Which of the velocity components (n

eglecting air resistance) remains constant throughout the flight?
Physics
2 answers:
DochEvi [55]2 years ago
6 0

Answer:

Horizontal component of velocity will remains conserved which is v = 12 m/s

Explanation:

Two components of velocity of the projectile is given as

\vec v = 20 cos53 \hat i + 20 sin53 \hat j

\vec v = 12\hat i + 16\hat j

now we know that the acceleration is only due to gravity as we are considering the force is only vertically downwards due to gravity and there is no air resistance during whole motion.

So we will have acceleration as

\vec a = 0\hat i - g\hat j

now we can say that here we do not have any acceleration along horizontal direction so this component of velocity will remain conserved.

So the constant component of velocity is along horizontal component and it is given by v = 12 m/s

Gekata [30.6K]2 years ago
5 0
Neglecting air resistance, the horizontal component remains constant. The angle doesn't matter.
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Hydraulic press is called an instrument for multiplication of force. Why?
Lisa [10]

Answer:

Hydraulic press is called an instrument for multiplication of force. Why? Because it uses Pascal's idea and  principle: F=p*S. If we apply small force to small piston you will generate a pressure. According to Pascal's law pressure is the same everywhere in closed system so the same pressure will act on large piston on the other side too.

Explanation:

4 0
2 years ago
Using energy considerations and assuming negligible air resistance, show that a rock thrown from a bridge 20.0 m above water wit
melamori03 [73]

Answer:

Explanation:

Given that,

Height of the bridge is 20m

Initial before he throws the rock

The height is hi = 20 m

Then, final height hitting the water

hf = 0 m

Initial speed the rock is throw

Vi = 15m/s

The final speed at which the rock hits the water

Vf = 24.8 m/s

Using conservation of energy given by the question hint

Ki + Ui = Kf + Uf

Where

Ki is initial kinetic energy

Ui is initial potential energy

Kf is final kinetic energy

Uf is final potential energy

Then,

Ki + Ui = Kf + Uf

Where

Ei = Ki + Ui

Where Ei is initial energy

Ei = ½mVi² + m•g•hi

Ei = ½m × 15² + m × 9.8 × 20

Ei = 112.5m + 196m

Ei = 308.5m J

Now,

Ef = Kf + Uf

Ef = ½mVf² + m•g•hf

Ef = ½m × 24.8² + m × 9.8 × 0

Ef = 307.52m + 0

Ef = 307.52m J

Since Ef ≈ Ei, then the rock thrown from the tip of a bridge is independent of the direction of throw

7 0
2 years ago
A hot–air balloon is moving at a speed of 10 meters/second in the +x–direction. The balloonist throws a brass ball in the +x–dir
IrinaVladis [17]
The ball has an initial speed of 10m/s. This is because it is moving with the balloon. Now the balloonist throws the ball 4m/s with respect to himself, so it means that he gives the ball a extra push of 4m/s, so the total speed is 14m/s. Since it takes 30 seconds to reach the ground, the distance travelled is 14*30=420m.
7 0
2 years ago
A boy on a bicycle approaches a brick wall as he sounds his horn at a frequency 400 hz. the sound he hears reflected back from t
Mashutka [201]
As the question is about changing in frequency of a wave for an observer who is moving relative to the wave source, the concept that should come to our minds is "Doppler's effect."

Now the general formula of the Doppler's effect is:
f = (\frac{g + v_{r}}{g + v_{s}})f_{o} -- (A)

Note: We do not need to worry about the signs, as everything is moving towards each other. If something/somebody were moving away, we would have the negative sign. However, in this problem it is not the issue.

Where,
g = Speed of sound = 340m/s.
v_{r} = Velocity of the receiver/observer relative to the medium = ?.
v_{s} = Velocity of the source with respect to medium = 0 m/s.
f_{o} =  Frequency emitted from source = 400 Hz.
f = Observed frequency = 408Hz.

Plug-in the above values in the equation (A), you would get:

408 = ( \frac{340 + v_{r}}{340 + 0})*400

\frac{408}{400} =  \frac{340 + v_{r}}{340}

Solving above would give you,
v_{r} = 6.8 m/s

The correct answer = 6.8m/s



7 0
2 years ago
What is the gravitational force of attraction between a planet and a 17-kilogram mass that is falling freely toward the surface
PolarNik [594]

Answer:

a. 150 N

Explanation:

Gravitational Force: This is the force that act on a body under gravity.

The gravitational force always attract every object on or near the earth's surface. The earth therefore, exerts an attractive force on every object on or near it.

The S.I unit of gravitational force is Newton(N).

Mathematically, gravitational force of attraction is expressed as

(i) F = GmM/r² ........................ Equation 1 ( when it involves two object of different masses on the earth)

(ii) F = mg ............................... Equation 2 ( when it involves one mass and the gravitational field).

Given: m = 17 kg, g = 8.8 m/s²

Substituting into equation 2,

F = 17(8.8)

F = 149.6 N

F ≈ 150 N.

Thus the gravitational force = 150 N

The correct option is a. 150 N

5 0
2 years ago
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