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4 years ago

To calculate the heat needed to melt a block of ice at its melting point what do you need to know?

Physics

1 answer:

777dan777 [17]4 years ago

5 0

Answer:

D.The mass and the latent heat of fusion.

Explanation:

When a block of ice is at its melting point, it doesn't need any additional heat in order to reach that temperature. Instead, it needs heat in order to break the bonds between the molecules and change state from solid to liquid. During the phase change, the temperature of the substance does not change, since all the heat provided is used to break the bonds between the molecules.

The heat needed for the phase change is

$Q=m\lambda_f$

where

m is the mass of the block

$\lambda_f$ is the latent heat of fusion

Therefore, we see that the correct answer is

D.The mass and the latent heat of fusion.

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Any person for the job he applied Force moment or torque

VLD [36.1K]

Answer:

i think torque is the answer not confirmed

7 0

3 years ago

A bus travels a distance of 120 km with a speed of 40km per hour and returns with a speed of 30km per hour calculate the average

Vsevolod [243]

Answer:

35 km/hr

Explanation:

Average speed = (total of the speed)/(the sets of speeds given)

Direction does not matter in this instance since speed is only magnitude,

Average speed = (30 + 40)/2

Average speed = 70 ÷ 2

= 35 km/hr

3 0

3 years ago

Does the efficiency of a motor depend on mass?

Valentin [98]

Practically yes

Efficiency=Output/input

If mass is more output may come less so it affects the efficiency practically

But thepritically it doesn't

5 0

2 years ago

Read 2 more answers

A car with a mass of 2000 kg is moving around a circular curve at a uniform velocity of 25 m/s per second. The curve has a radiu

IrinaK [193]

The centripetal force is:
F = mv² / R
Where:
m: mass of the object
v: object speed
R: radius of the curve.
We have to:
m = 2000kg
v = 25 m / s
R = 80 meters.
Then the centripetal force acting on the vehicle is:
F = (2000kg * (25m / s) ²) / 80m
F = 15625 N

4 0

3 years ago

In pairs figure-skating competition, a 65-kg man and his 45-kg female partner stand facing each other both at rest on the ice. I

Lina20 [59]

Answer:

The final velocity of her partner is approximately -1.04 m/s or 1.04 m/s in the opposite direction to her direction of motion

Explanation:

The given parameters are;

The mass of the man, m₁ = 65 kg

The mass of the woman, m₂ = 45 kg

Taking the relative initial velocity of the man and the woman as 0 m/s, we have;

The initial velocity of the man, v₁₁ = 0 m/s

The initial velocity of the man, v₁₂ = 0 m/s

The final velocity of the woman, v₂₂ = 1.5 m/s

The final velocity of the man = v₂₁

Therefore, we have, by the conservation of momentum principle;

The total initial momentum = The total final momentum

Which gives;

m₁ × v₁₁ + m₂ × v₁₂ = m₁ × v₂₁ + m₂ × v₂₂

Substituting the known values;

65 × 0 + 45 × 0 = 65 × v₂₁ + 45 × 1.5

∴ 65 × v₂₁ + 45 × 1.5 = 0

45 × 1.5 = - 65 × v₂₁

v₂₁ = 45 × 1.5/(-65) ≈ -1.04 m/s

The final velocity of the man, her partner = v₂₁ ≈ -1.04 m/s.

6 0

3 years ago