Ask question

Ask question

All categories

4 years ago

13

Why does ice float on water? a.The temperature of ice is lower than the temperature of water b.The temperature of water and ice

are the same c.The density of ice is less than the density of water d.The density of ice is greater than the density of water

1 answer:

pav-90 [236]4 years ago

7 0

The density of ice is less than the density of water. C

You might be interested in

In a local bar, a customer slides an empty beer mug down the counter for a refill. The height of the counter is 1.46 m. The mug

Tresset [83]

Answer:

(a). The horizontal velocity is 1.46 m/s.

(b). The direction of the mug's velocity just before it hit the floor is 74.7° below the horizontal.

Explanation:

Given that,

Height of the counter = 1.46 m

Distance = 0.80 m

We need to calculate the time

Using equation of motion

$s_{y}=ut+\dfrac{1}{2}gt^2$

$s_{y}=\dfrac{1}{2}gt^2$

Put the value into the formula

$1.46=\dfrac{1}{2}\times9.8\times t^2$

$t^2=\dfrac{1.46\times 2}{9.8}$

$t=\sqrt{\dfrac{1.46\times2}{9.8}}$

$t=0.545\ sec$

Here, horizontal velocity is constant

(a). We need to calculate the velocity

Using formula of velocity

$v_{x}=\dfrac{d}{t}$

Put the value into the formula

$v_{x}=\dfrac{0.80}{0.545}$

$v_{x}=1.46\ m/s$

(b). We need to calculate the final velocity

Using equation of motion

$v_{f}^2=u^2+2as$

Put the value into the formula

$v_{f}^2=0+2\times9.8\times1.46$

$v_{f}=\sqrt{28.616}$

$v_{f}=5.34\ m/s$

The velocity is 5.34 m/s downward.

We need to calculate the direction

Using formula of direction

$\tan\theta=\dfrac{v_{y}}{v_{x}}$

$\theta=\tan^{-1}(\dfrac{5.34}{1.46})$

$\theta=74.7^{\circ}$

Hence, (a). The horizontal velocity is 1.46 m/s.

(b). The direction of the mug's velocity just before it hit the floor is 74.7° below the horizontal.

5 0

4 years ago

A 25 kg box on a horizontal frictionless surface is moving to the right at a speed of 5.0 m s. The box hits and remains attached

seropon [69]

Answer:

Explanation:

Work done by the spring is negative .

Work done by force F creating displacement d is given by the following expression .

Work = F x d

Both force and displacement are vector quantity .

When direction of force and direction of displacement is same , work is positive . When direction of force and direction of displacement is opposite , work is negative .

When spring is compressed , it exerts a restoring or opposing force in a direction opposite to the direction of displacement of box . Hence here force is opposite to displacement . Restoring force acts opposite to displacement . Hence work done by spring on box is negative .

6 0

3 years ago

2.5 g of helium at an initial temperature of 300 K interacts thermally with 9.0 g of oxygen at an initial temperature of 620 K .

muminat

Answer:

Explanation:

2.5 g of He = 2.5 / 4 mole

= .625 moles

9 g of oxygen = 9/32

= .28 mole of oxygen

C_p of He = 3/2 R

C_p of O₂ = 5/2 R

A ) Initial thermal energy of He = 3/2 n R T

= 1.5 x .625 x 8.32 x 300

= 2340 J

Initial thermal energy of O₂ = 5/2 n R T

= 2.5 x .28 x 8.32 x 620

= 3610.88 J

B ) If T be the equilibrium temperature after mixing

gain of heat by helium

= n C_p Δ T

= .625 x 3/2 R x ( T - 300 )

Loss of heat by oxygen

n C_p Δ T

= .28 x 5/2 R x ( 620 - T )

Loss of heat = gain of heat

.625 x 3/2 R x ( T - 300 ) = .28 x 5/2 R x ( 620 - T )

1.875 T- 562.5 = 868- 1.4 T

3.275 T = 1430,5

T = 436.8 K

Thermal energy of He

= 1.5 x .625 x 8.32 x 436.8

= 3407 J

thermal energy of O₂

= 2.5 x .28 x 8.32 x 436.8

= 2543.92 J

C )

Heat energy transferred

= .28 x 5/2 R x ( 620 - T )

= .28 x 5/2 x 8.32 x ( 620 - 436.8 )

1066.95 J

Heat will flow from O₂ to He

Final temperature is 436.8 K

7 0

3 years ago

When current flows through an electric motor, the electromagnet rotates. true or false?

Arte-miy333 [17]

Answer: true

Explanation:

It helping it rotate

6 0

3 years ago

What is the value of coefficient of friction force

san4es73 [151]

Answer:

<h2>There is a frictional force between two objects that are not in relative motion. Such a force is called the static friction force.</h2><h2>There is a frictional force between two objects that are not in relative motion. Such a force is called the static friction force....</h2><h2>There is a frictional force between two objects that are not in relative motion. Such a force is called the static friction force....Friction coefficients.</h2><h2>There is a frictional force between two objects that are not in relative motion. Such a force is called the static friction force....Friction coefficients.MATERIAL S K</h2><h2>There is a frictional force between two objects that are not in relative motion. Such a force is called the static friction force....Friction coefficients.MATERIAL S KMetal on leather 0.6 0.5</h2><h2>There is a frictional force between two objects that are not in relative motion. Such a force is called the static friction force....Friction coefficients.MATERIAL S KMetal on leather 0.6 0.5Wood on leather 0.5 0.4</h2><h2>There is a frictional force between two objects that are not in relative motion. Such a force is called the static friction force....Friction coefficients.MATERIAL S KMetal on leather 0.6 0.5Wood on leather 0.5 0.4Rubber on concrete, dry 0.9 0.7</h2><h2>There is a frictional force between two objects that are not in relative motion. Such a force is called the static friction force....Friction coefficients.MATERIAL S KMetal on leather 0.6 0.5Wood on leather 0.5 0.4Rubber on concrete, dry 0.9 0.7wet 0.7 0.57</h2>

Explanation:

<h2>Greetings, I'm from my beloved Mexico</h2>

3 0

3 years ago

Read 2 more answers