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2 years ago

5

What is the instantaneous velocity of a freely falling object 9.0 s after it is released from a position of rest? Express your a

nswer to two significant figures and include the appropriate units.

1 answer:

Umnica [9.8K]2 years ago

5 0

Answer:

So instantaneous velocity after 9 sec will be 88.2 m/sec

Explanation:

We have given time t = 9 sec

As the object is released from rest so its initial velocity u = 0 m/sec

We have to find its final velocity v

Acceleration due to gravity $g=9.8m/sec^2$

From first equation of motion we know that $v=u+gt$

$v=0+9.8\times 9=88.2m/sec$

So instantaneous velocity after 9 sec will be 88.2 m/sec

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You toss a rock of mass m vertically upward. Air resistance can be neglected. The rock reaches a maximum height h above your han

VladimirAG [237]

Answer with Explanation:

We are given that

Mass of rock=m

Maximum height=h

a.At maximum height, velocity,v=0

We know that

$v^2=u^2-2gh$

$0+2gh=u^2$

$u^2=2gh$

Height,h=h/4

Again, $v'^2=u^2-2g\times \frac{h}{4}$

$v'^2=2gh-\frac{gh}{2}=\frac{4gh-gh}{2}=\frac{3gh}{2}$

$v'=\sqrt{\frac{3gh}{2}}=\sqrt{\frac{3\times 9.8 h}{2}}=3.83\sqrt h$

Where $g=9.8 m/s^2$

b.When height,h=3h/4

$v'^2=u^2-2gh$

$v'^2=2gh-2g\times \frac{3h}{4}=2gh-\frac{3gh}{2}=\frac{4gh-3gh}{2}=\frac{gh}{2}$

$v'=\sqrt{\frac{9.8h}{2}}=2.2\sqrt h$

$v'=2.2\sqrt h$

4 0

2 years ago

Read 2 more answers

Romeo lanza suavemente guijarros a la ventana de julieta y quiere que los guijarros golpeen la ventana solo con con un component

Yuki888 [10]

Answer:

$5.219\,\frac{m}{s}$

Explanation:

Las condiciones del problema requieren el cálculo de la rapidez inicial de los guijarros. Se sabe que el componente vertical de la rapidez final es cero. Por tanto, el tiempo se determina a continuación: (The conditions of this problems require the calculation of the initial speed of the peebles. It is known that vertical component of the final speed is zero. Therefore, the time is determined herein:).

$(0\,\frac{m}{s})^{2} = v_{o,y}^{2} - 2\cdot \left(9.807\,\frac{m}{s^{2}} \right)\cdot (4.5\,m)$

$v_{o,y} = 9.395\,\frac{m}{s}$

$0\,\frac{m}{s} = 9.395\,\frac{m}{s} - \left(9.807\,\frac{m}{s^{2}} \right)\cdot \Delta t$

$\Delta t = 0.958\,s$

Además, se determina el componente horizontal de la rapidez inicial (Likewise, the horizontal component of the initial speed is determined):

$v_{o,x} = \frac{5\,m}{0.958\,s}$

$v_{o,x} = 5.219\,\frac{m}{s}$

El guijarro tiene una rapidez de $5.219\,\frac{m}{s}$ cuando golpea la ventana (The peeble has a speed of $5.219\,\frac{m}{s}$ when it hits the window).

6 0

2 years ago

What are physical forms in which a substance can exist?

Alecsey [184]

Physical forms are: gas,liquid,and solid

8 0

2 years ago

A 1500 kg car traveling at 20 m/s suddenly runs out of gas while approaching the valley shown in the figure. The alert driver im

geniusboy [140]

Answer:

v_f = 17.4 m / s

Explanation:

For this exercise we can use conservation of energy

starting point. On the hill when running out of gas

Em₀ = K + U = ½ m v₀² + m g y₁

final point. Arriving at the gas station

Em_f = K + U = ½ m v_f ² + m g y₂

energy is conserved

Em₀ = Em_f

½ m v₀ ² + m g y₁ = ½ m v_f ² + m g y₂

v_f ² = v₀² + 2g (y₁ -y₂)

we calculate

v_f ² = 20² + 2 9.8 (10 -15)

v_f = √302

v_f = 17.4 m / s

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2 years ago

The price of coffee fell sharply last month, while the quantity sold remained the same. Five people suggest various explanations

miss Akunina [59]

Answer:

France. True Supply increased and demand did not adapt

Explanation:

If the price of coffee decreases it may be due to two causes

- Increase of the offer

- decrease in demand

- both simultaneously.

Let's examine the statement. They tell us that the amount sold remained constant, so there is no decrease in demand, therefore the only cause may be the increase in supply.

Let's check the answers

Antonio False. The demand is constant.

Carolina. False. The demand is constant.

Dmitri False. The demand is constant.

France. True Supply increased and demand did not adapt

Jake. False. Demand did not adapt to the increase in supply

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2 years ago