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3 years ago

On the way to school, the bus speeds up from 20 m/s to 36 m/s in 4 seconds. What distance does the bus cover in this time frame

Physics

1 answer:

Fantom [35]3 years ago

3 0

Answer:

Explanation:

initial velocity u = 20 m /s

final velocity v = 36 m /s

time taken t = 4 s .

acceleration = (v - u) / t

= (36 - 20) / 4

a = 4 m / s ²

from the formula

v² - u² = 2 a s , s is distance covered .

putting the values

36² - 20² = 2 x 4 x s

1296 - 400 = 8 x s

s = 112 m .

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Water runs through a plumbing with a flow of 0.750m3/s and arrives to every exit of a fountain. At what speed will the water com

Lubov Fominskaja [6]

Divide the flow rate (0.750 m³/s) by the cross-sectional area of each pipe:

diameter = 40 mm ==> area = π (0.04 m)² ≈ 0.00503 m²

diameter = 120 mm ==> area = π (0.12 m)² ≈ 0.0452 m²

Then the speed at the end of the 40 mm pipe is

(0.750 m³/s) / (0.00503 m²) ≈ 149.208 m/s ≈ 149 m/s

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3 years ago

mass of the planet is 12 times that of earth and its radius is thrice that of earth , then find the escape velocity on that plan

Over [174]

Answer:

The escape velocity on the planet is approximately 178.976 km/s

Explanation:

The escape velocity for Earth is therefore given as follows

The formula for escape velocity, $v_e$ , for the planet is $v_e = \sqrt{\dfrac{2 \cdot G \cdot m}{r} }$

Where;

$v_e$ = The escape velocity on the planet

G = The universal gravitational constant = 6.67430 × 10⁻¹¹ N·m²/kg²

m = The mass of the planet = 12 × The mass of Earth, $M_E$

r = The radius of the planet = 3 × The radius of Earth, $R_E$

The escape velocity for Earth, $v_e_E$ , is therefore given as follows;

$v_e_E = \sqrt{\dfrac{2 \cdot G \cdot M_E}{R_E} }$

$\therefore v_e = \sqrt{\dfrac{2 \times G \times 12 \times M}{3 \times R} } = \sqrt{\dfrac{2 \times G \times 4 \times M}{R} } = 16 \times \sqrt{\dfrac{2 \times G \times M}{R} } = 16 \times v_e_E$

$v_e$ = 16 × $v_e_E$

Given that the escape velocity for Earth, $v_e_E$ ≈ 11,186 m/s, we have;

The escape velocity on the planet = $v_e$ ≈ 16 × 11,186 ≈ 178976 m/s ≈ 178.976 km/s.

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3 years ago

What is the speed of a wave frequency of 300hz and a wavelength of 25M

tia_tia [17]

Answer:

7500 m/s

Explanation:

We can use the equation velocity of a wave equals wavelength times frequency. Therefore, v = wavelength*f = (25 m)(300 Hz) = m/s7,500

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3 years ago

A child on a sled is perched at the top of a hill, at a height 7.0 m above the base of the hill. The total mass of the girl plus

spin [16.1K]

Answer:

a)11,71 m/s

b)12.73 m/s

Explanation:

We apply the conservation principle because there is no friction between the hill and the sled:

Total initial energy (Ei) = Total initial energy (Ef), Equation(1)

We define:

K = Kinetic energy = $\frac{1}{2}*m*v^{2}$

U = Potential energy = $m*g*h$

m = mass (kg)

v = velocity (m/s)

h = height (m)

g = gravity acceleration = $9.8m/s^{2}$

A) hi=7m, hf=0 ,vi=0 , vf=?

$Ei=Ef\\Ki+Ui=Kf+Uf$

$1/2*m*vi^{2} +m*g*hi= 1/2*m*vf^{2} +m*g*hf$

$0+m*g*hi=1/2*m*vf^{2}+0$

$(2*m*g*hi)/m=vf^{2}$

$vf=\sqrt{2*g*hi}$

$vf=\sqrt{2*9.8*7}$

$vf=11.71 m/s$

Answer: She reaches the base of the hill with speed of 11.22 m/s

B) hi=7 m, vi=5 m/s, hf=0, vf=?

$m*g*hi+1/2*m*vi^{2} =m*g*hf+1/2*m*vf^{2}$

We divide all terms by m

$g*hi+1/2vi^{2} =g*hf+1/2*vf^{2}$

$9.8*7+1/2*5^{2} =1/2*vf^{2}$

$2(68.6+12.5)=vf^{2}$

$162.2=vf^{2}$

$vf=\sqrt{162.2}$

$vf=12.73 m/s$

Answer: She will move with a speed of 12.73 m/s when she reaches the base of the hill

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3 years ago