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lidiya [134]
3 years ago
7

A car traveling 85 km/h slows down at a constant 0.47 m/s^2 just by "letting up on the gas."​ Calculate the distance it travels

during the first second. Express your answer to two significant figures and include the appropriate units. Calculate the distance it travels during the fifth second.
Physics
1 answer:
Tcecarenko [31]3 years ago
5 0

Answer:

Explanation:

u = 85 km / h = 23.61 m /s

Acceleration a = - 0.47 m /s²

Distance travelled in n th sec

S_n = u + ( 2t -1 )a/2

S_n is distance travelled in n th seond

Distance traveled in 1 st second

= 23.61 - .5 x .47

= 23.37  m

=23  m

Distance travelled when t = 5 th

= 23.61 - (2x5 -1)/2 x .47

= 23.61 - 4.5 x .47

23.61 -2.115

=21.495

21 m  is distance travelled in  5 th second .

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Explain how convection currents help mushrooms reproduce. Which spheres are interacting in this example?
g100num [7]

<span>The Convection currents is a Currents of heat that radiate to the Earth's crust and Caused by the core.  Core is hotter than the mantle and made of iron which convection currents move the plates is hot stuff up cold sinks, and its hotness makes the mushrooms reproduce. </span>

7 0
3 years ago
A hand pump is being used to inflate a bicycle tire that has a gauge pressure of 41.0 lb/in2. If the pump is a cylinder of lengt
damaskus [11]

Answer:

L - h = 12.3672 in

Explanation:

Given

P = 41.0 lb/in² = 41 P.S.I

L = 16.8 in

A = 3.00 in²

h = ?

In order that air flows into the tire, the pressure in the pump must be more than the tire pressure,  41.0  PSI.

We assume that air follows ideal gas equation, the temperature of the compressed air remains constant as the piston moves down. Taking one atmospheric pressure to be  14.6959  P.S.I , we can use the ideal gas equation

P*V = n*R*T

As number of moles of air do not change during its compression in the pump, n*R*T of the gas equation is constant. Therefore we have

P₁*V₁ = P₂*V₂    ⇒    V₂ = P₁*V₁ / P₂

where  

1  and  2  are initial and final states respectively,

V₁ = A*L = (3.00 in²)*(16.8 in)   ⇒   V₁ = 50.4 in³

P₁ = 14.6959  P.S.I

P₂ = P₁ + P = (14.6959 lb/in²) + (41.0 lb/in²) = 55.6959 lb/in²

Inserting various values we get

V₂ = (14.6959  P.S.I)*(50.4 in³) / (55.6959 lb/in²)

⇒  V₂ = 13.2985 in³

Length of pump, measured from bottom, this volume corresponds to is

h = V₂ / A  = (13.2985 in³) / (3.00 in²)

⇒  h = 4.4328 in

Piston must be pushed down by more than

L - h = 16.8 in - 4.4328 in = 12.3672 in

4 0
3 years ago
Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the 3.0-kg mass i
Fed [463]

Answer:25 N

Explanation:

Given

mass of 5 , 3 & 2 kg blocks lie on floor

Force on 50 N pushes the 5 kg box

Let N_1 be the reaction on 2 kg box therefore

N_1=2\times a

where a is the acceleration of the system

N_2=reaction on 3 kg block by 5 kg block

N_2-N_1=3a

N_2=5a

Now for 5 kg block

F-N_2=5a

F=10a

a=\frac{F}{10}=5 m/s^2

Force exerted by 5 kg block on 3 kg block is

N_2=5\times 5=25 N

6 0
3 years ago
Find the density of a planet with a radius of 8000 m if the gravitational acceleration for the planet, gp, has the same magnitud
Naya [18.7K]

Answer:

Density = 3 x 10⁻⁵ kg/m³

Explanation:

First, we will find the volume of the planet:

V = \frac{4}{3}\pi r^3\ (radius\ of\ sphere)\\\\V =   \frac{4}{3}\pi (8000\ m)^3\\\\V = 2.14\ x\ 10^{12}\ m^3

Now, we will use the expression for gravitational force to find the mass of the planet:

g = \frac{Gm}{r^2}\\\\m = \frac{gr^2}{G}

where,

m = mass = ?

g = acceleration due to gravity = 6.67 x 10⁻¹¹ m/s²

G = Universal Gravitational Constant = 6.67 x 10⁻¹¹ Nm²/kg²

r = radius = 8000 m

Therefore,

m = \frac{(6.67\ x\ 10^{-11}\ m/s^2)(8000\ m)^2}{6.67\ x\ 10^{-11}\ Nm^/kg^2}\\\\m = 6.4\ x\ 10^7\ kg

Therefore, the density will be:

Density = \frac{m}{V} = \frac{6.4\ x\ 10^7\ kg}{2.14\ x\ 10^{12}\ m^3}

<u>Density = 3 x 10⁻⁵ kg/m³</u>

4 0
3 years ago
A neutron in a nuclear reactor makes an elastic head-on collision with the nucleus of a plutonium atom initially at rest. (a) Wh
olga55 [171]

Answer:

Fraction = 59049/60025

Explanation:

Let m be the mass of the neutron and M be the mass of the plutonium nucleus (at rest)

Now, formula for kinetic energy before collision is;

K_i = ½mu²

Formula for kinetic energy after collision is;

K_f = ½mv²

Where;

u is the velocity of the neutron before collision

v is the velocity of the neutron after collision.

From collision principle where momentum before collision equals momentum after collision, we can say that;

(m - M)u = (m + M)v

Thus,

v = [(m - M)u]/(m + M)

Putting [(m - M)u]/(m + M) for v in the final kinetic energy equation gives;

K_f = ½m([(m - M)u]/(m + M))²

K_f = ½mu²((m - M)²/(m + M)²)

To get the fraction of the neutron's kinetic energy is transferred to the plutonium nucleus, it is simply;

K_f/K_i = [½mu²((m - M)²/(m + M)²)]/½mu²

This gives;

K_f/K_i = ((m - M)²/(m + M)²)

But mass of plutonium = 244m

Thus;

K_f/K_i = ((m - 244m)²/(m + 244m)²)

K_f/K_i = 59049m²/60025m²

K_f/K_i = 59049/60025

4 0
3 years ago
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