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2 years ago

If a ball was thrown upward at 46.3 m/s how long would the ball stay in the air

1 answer:

8 0

$V = Vo + a.t

$

The ball is against the vector of gravity. Then, the gravity will be negative.

$0 = 46,3 + (-9.8).t \\ 
t = \frac{46.3}{9.8} \\ 
t \approx 4.72 

$

The ball will stop in the air after approx. 4.72 seconds. And will take the same time to hit the ground.

It will stay approx. 9.44 seconds in the air.

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carbon-14 has a half-life of approximately 5,700 years. a fossil shell contain 25% of the original amount of its carbon-14. appr

denis23 [38]

The half-life equation $m=m_{0} (\frac{1}{2})^n$ in which n is equal to the number of half-lives that have passed can be altered to solve for n.

$n = \frac{log(\frac{m}{m_{0}} )}{log(\frac{1}{2})}$

$\frac{log(\frac{.25}{1} )}{log(\frac{1}{2})} = 2$

Then, the number of half-lives that passed can be multiplied by the length of a half-life to find the total time.

2 * 5700 = 11400 yr

3 0

2 years ago

Bricks and insulation are used to construct the walls of a house. The

ira [324]

Answer:

$\dot Q=350.438\ W$

Explanation:

Given:

the thermal resistance in the form of

$R_1=\frac{x_1}{k_1} =0.095\ m^2.^{\circ}C.W^{-1}$

$R_2=\frac{x_2}{k_2} =0.704\ m^2.^{\circ}C.W^{-1}$

where:

$x_1\ \&\ x_2$ are the thickness of the respective bricks

$k_1\ \&\ k_2$ are the respective coefficient of conductivity

temperature inside the house, $T_h=24\ ^{\circ}C$

temperature outside the house, $\ T_c=10^{\circ}C$

area of the wall, $A=20\ m^2$

Since the bricks and insulation are used to construct a wall then they must be used in series for better shielding.

Using Fourier's law:

$\dot Q=k.A.\frac{dT}{x}$

$\dot Q={dT}\div {\frac{x}{k.A} }$

in series the resistances get add up

$\dot Q=dT\div (\frac{x_1}{k_1.A}+\frac{x_2}{k_2.A} )$

$\dot Q=(24-10)\div (\frac{0.095 }{20}+ \frac{0.704 }{20} )$

$\dot Q=350.438\ W$

7 0

2 years ago

Imagine you want to get 1 kcal of energy from a cow. How much energy would the cow need to get from plants? Why?

ZanzabumX [31]

1000 kcal because you only get 10% of the energy of the thing you eat

7 0

2 years ago

Because the soles of your shoes have cleats, you can exert a forward force of 100 N even on slippery ice. A 10-kg picnic cooler

Brilliant_brown [7]

Answer:

you must throw 3 snowballs

Explanation:

We can solve this exercise using the concepts of conservation of the moment, let's define the system as formed by the refrigerator and all the snowballs. Let's write the moment

Initial. Before bumping that refrigerator

p₀ = n m v₀

Where n is the snowball number

Final. When the refrigerator moves

pf = (n m + M) v

The moment is preserved because the forces during the crash are internal

n m v₀ = (n m + M) v

n m (v₀ - v) = M v

n = M/m v/(vo-v)

Let's look for the initial velocity of the balls, suppose the person throws them with the maximum force if it slides in the snow (F = 100N), let's use the second law and Newton

F = m a

a = F / m

The distance the ball travels from zero speed to maximum speed is the extension of the arm (x = 1 m), let's look kinematically for the speed of the balls when leaving the arm

v₁² = v₀² + 2 a x

v₁² = 0+ 2 (100/1) 1

v₁ = 14.14 m / s

This is the initial speed for the crash

v₀ = v = 14.14 m / s

Let's calculate

n = M/m v/ (v₀-v)

n = 10/1 3 / (14.14 -3)

n = 2.7 balls

you must throw 3 snowballs

7 0

2 years ago

A bulldozer does 4,500 J of work to push a mound of soil to the top of a ramp that is 15 m high. The ramp is at an angle of 35°

spin [16.1K]

Answer

Force = 170 N

Explanation

First find the distance (d) travelled by the bulldozer.

Sin 35 = 15/d

d = 15/(sin 35)

= 26.15m

Now;

work done = force × distance.

4500 J = force × 26.15

dividing both sides by 26.15,

Force = 4500/26.15

= 172.07 N

Answer to two significant figures = 170 N

3 0

2 years ago

Read 2 more answers