The specific gravity of mantle rock is about 3.3. True False

The length of a brick is 30cm,breadth 20 cm and volume 9000 cm³.Find the height of the brick.

kondor19780726 [428]

Answer:

l=30cm

w=20cm

v=9000cm³

h=?

according to formula

h=V/A

h=9000/(30×20) ∴A=l×w

h=9000/600

h=15cm

mark as brainliest plz

6 0

3 years ago

A dog pushes a toy horizontally on a frictionless floor with a net force of 2.0\, \text N2.0N for 1.0\,\text m1.0m. How much kin

IRINA_888 [86]

Answer:

2.0 J

Explanation:

Since the surface is frictionless, we can solve the problem by using the work-energy theorem, which states that the work done on the toy is equal to the kinetic energy gained by the toy:

$W=\Delta E_k$

where

W is the work done on the toy

$\Delta E_k$ is the kinetic energy gained by the toy

The work done can be calculated as the product between the force applied on the toy and its displacement, so:

$W=Fd=(2.0 N)(1.0 m)=2.0 J$

Therefore, according to the work-energy theorem, the toy has gained 2.0 J of kinetic energy.

4 0

3 years ago

Read 2 more answers

A reciprocating compressor is a device that compresses air by a back-and-forth straight-line motion, like a piston in a cylinder

Stella [2.4K]

Answer:

The temperature change per compression stroke is 32.48°.

Explanation:

Given that,

Angular frequency = 150 rpm

Stroke = 2.00 mol

Initial temperature = 390 K

Supplied power = -7.9 kW

Rate of heat = -1.1 kW

We need to calculate the time for compressor

Using formula of compression

$\terxt{time for compression}=\text{time for half revolution}$

$\terxt{time for compression}=\dfrac{1}{2}\times T$

$\terxt{time for compression}=\dfrac{1}{2}\times \dfrac{1}{f}$

Put the value into the formula

$\terxt{time for compression}=\dfrac{1}{2}\times \dfrac{1}{150}\times60$

$\terxt{time for compression}=0.2\ sec$

We need to calculate the rate of internal energy

Using first law of thermodynamics

$U=Q-W$

$\dfrac{\Delta U}{\Delta t}=\dfrac{\Delta Q}{\Delta t}-\dfrac{\Delta W}{\Delta t}$

Put the value into the formula

$\dfrac{\Delta U}{\Delta t}=(-1.1)-(7.9)$

$\dfrac{\Delta U}{\Delta t}=6.8\ kW$

We need to calculate the temperature change per compression stroke

Using formula of rate of internal energy

$\dfrac{\Delta U}{\Delta t}=\dfrac{nc_{v}\Delta \theta}{\Delta t}$

$\Delta\theta=\dfrac{\Delta U}{\Delta t}\times\dfrac{\Delta t}{n\times c_{c}}$

Put the value into the formula

$\Delta \theta=6.8\times10^{3}\dfrac{0.2}{2.0\times20.93}$

$\Delta\theta=32.48^{\circ}$

Hence, The temperature change per compression stroke is 32.48°.

6 0

3 years ago

A motor develops 80 kW of power as it lifts a loaded elevator 20.5 m in 45 s. How much force does the motor exert? *

yuradex [85]

Answer:

F=1.3⋅105N

Explanation:

It's common knowledge.

7 0

3 years ago

The near point of a person's eye is 71.4 cm. To see objects clearly at a distance of 24.0 cm, what should be the focal length an

yuradex [85]

Answer:

The focal length of the appropriate corrective lens is 35.71 cm.

The power of the appropriate corrective lens is 0.028 D.

Explanation:

The expression for the lens formula is as follows;

$\frac{1}{f}=\frac{1}{u}+\frac{1}{v}$

Here, f is the focal length, u is the object distance and v is the image distance.

It is given in the problem that the given lens is corrective lens. Then, it will form an upright and virtual image at the near point of person's eye. The near point of a person's eye is 71.4 cm. To see objects clearly at a distance of 24.0 cm, the corrective lens is used.

Put v= -71.4 cm and u= 24.0 cm in the above expression.

$\frac{1}{f}=\frac{1}{24}+\frac{1}{-71.4}$