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3 years ago

Which statement about projectile motion is true?

Physics

2 answers:

Shalnov [3]3 years ago

4 0

Answer:

D. The hang time of a projectile is greatest for a vertical launch.

Explanation:

As we know that range of projectile is given by the formula

$R = \frac{v^2sin(2\theta)}{g}$

so here as we increase the angle till 45 degree then the range will decrease but if we increase the angle more than 45 degree then the range will start decreasing

Also we know that time of flight is given by the formula

$T = \frac{2vsin\theta}{g}$

since it depends on the vertical component of the motion so we can say that hang time can be determine by vertical components of the motion

So maximum hang time is possible only when angle of projection is 90 degree

so correct answer will be

D. The hang time of a projectile is greatest for a vertical launch.

Svetllana [295]3 years ago

3 0

C. The range of a projectile increases with an increase in the angle of launch.

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In a heat engine, Qh and Qc represents high temperature substance and low temperature substance respectively. Which of the follo

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The efficiency of a heat engine is given by the expression $eff =\frac{Q_h-Q_c}{Q_h}$

The efficiency of a heat engine is the ratio of the work done by the engine to the heat given as the input to the engine.

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Therefore, the work done is given by,

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3 years ago

Show explicitly that ▽ . B-0 near a long straight wire carrying a current I. HINT: you may use Cartesian coordinates, but anothe

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Answer:

$\bigtriangledown.B=0$ is proved.

Explanation:

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Now, by using cylindrical coordinates for the divergence of B.

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Put the value of B in above equation.

$\bigtriangledown.B=\frac{1}{s} \frac{d}{d\phi}(\frac{\mu_{0}I }{2\pi r } \phi)\\\bigtriangledown.B=0$

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3 years ago

Two identical loudspeakers are driven in phase by the same amplifier. The speakers are positioned a distance of 3.2 m apart. A p

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Answer:

f = 735 Hz

Explanation:

given,

Person distance from speakers

r₁ = 4.1 m r₂ = 4.8 m

Path difference

d = r₂ - r₁ = 4.8 - 4.1 = 0.7 m

For destructive interference

$d = \dfrac{n\lambda}{2}$

where, n = 1, 3,5..

we know, λ = v/f

$d = \dfrac{n v}{2f}$

v is the speed of the sound = 343 m/s

f is the frequency

$f = \dfrac{n v}{2d}$

for n = 1

$f = \dfrac{343}{2\times 0.7}$

f = 245 Hz

for n = 3

$f = \dfrac{3\times 343}{2\times 0.7}$

f = 735 Hz

Hence,the second lowest frequency of the destructive interference is 735 Hz.

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4 years ago

A man is standing on the edge of a 20.0 m high cliff. He throws a rock horizontally with an initial velocity of 10.0 m/s.

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Answer:

a. The rock takes 2.02 seconds to hit the ground

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The time taken by the object to hit the ground is calculated by:

$\displaystyle t=\sqrt{\frac{2h}{g}}$