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3 years ago

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Physics

1 answer:

Sever21 [200]3 years ago

8 0

1. area of exposure

2. temp difference

3. thickness of the material

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borishaifa [10]

Answer:

uh huh???

Explanation:

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3 years ago

A hollow plastic sphere is held below the surface of a fresh-water lake by a cord anchored to the bottom of the lake. The sphere

Naya [18.7K]

Answer: a) B = 6811N

b) m = 603.2kg

c) 86.8%

Explanation: Buoyant force is a force a fluid exerts on a submerged object.

It can be calculated as:

$B=\rho_{fluid}.V_{obj}.g$

where:

$\rho_{fluid}$ is density of the fluid the object is in;

$V_{obj}$ is volume of the object;

g is acceleration due to gravity, is constant and equals 9.8m/s²

a) For the hollow plastic sphere, density of water is 1000kg/m³:

$B=10^{3}.0.695.9.8$

B = 6811N

b) Anchored to the bottom, the forces acting on the sphere are Buoyant, Tension and Force due to gravity:

B = T + $F_{g}$

B = T + mg

mg = B - T

$m=\frac{B - T}{g}$

Calculating:

$m=\frac{6811 - 900}{9.8}$

m = 603.2kg

c) When the shpere comes to rest on the surface of the water, there are only buoyant and gravity acting on it:

B = m.g

$\rho_{w}.V_{sub}.g=m.g$

$V_{sub}=\frac{m}{\rho_{w}}$

$V_{sub}=\frac{603.2}{1000}$

$V_{sub}$ = 0.6032m³

Fraction of the submerged volume is:

$\frac{V_{sub}}{V_{obj}}$ = $\frac{0.6932}{0.695}$ = 0.868

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3 years ago

Suppose 1 kg of Hydrogen is converted into Helium. a) What is the mass of the He produced? b) How much energy is released in thi

morpeh [17]

Answer:

a) m = 993 g

b) E = 6.50 × 10¹⁴ J

Explanation:

atomic mass of hydrogen = 1.00794

4 hydrogen atom will make a helium atom = 4 × 1.00794 = 4.03176

we know atomic mass of helium = 4.002602

difference in the atomic mass of helium = 4.03176-4.002602 = 0.029158

fraction of mass lost = $\dfrac{0.029158}{4.03176}$ = 0.00723

loss of mass for 1000 g = 1000 × 0.00723 = 7.23

a) mass of helium produced = 1000-7.23 = 993 g (approx.)

b) energy released in the process

E = m c²

E = 0.00723 × (3× 10⁸)²

E = 6.50 × 10¹⁴ J

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3 years ago

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If this speed is based on what would be safe in wet weather, estimate the radius of curvature for a curve marked 70 km/h . The c

olganol [36]

as it is given that curved marked the speed as v = 70 km/h

so we will first convert the speed into m/s

$v = 70 km/h = 19.44 m/s$

now we know that here friction force will provide centripetal force

$F_c = F_f$

As we know that centripetal force is given as

$F_c = \frac{mv^2}{R}$

$\frac{mv^2}{R} = \mu_k mg$

$\frac{v^2}{R} = \mu_k g$

$v^2 = \mu_k R * g$

$19.44^2 = 0.5* R * 9.8$

$378 = 4.9 * R$

$R = 77.1 m$

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Why do windows of distant houses appear to reflect the sun only when rising or setting

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most importantly, the sun is reflected back at the same angle as the angle of incidence, so with vertical panes of glass and the sun overhead, the reflection will just hit the ground before traveling any distance.

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3 years ago

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