Last month Dr. Hruda's electric bill showed that she used 249 kW-hr. How many Joules (kJ) did Dr. Hruda use?

What is the kinetic energy of a 150 gram object moving at a velocity of 100 m/s?

Alex Ar [27]

Answer:

750 J

Explanation:

lets convert mass into kg first , 150 /1000 = 0.15 kg

kinetic energy = $\frac{mv^{2} }{2}$ = $\frac{0.15*100^{2} }{2} = 750 J$

3 0

3 years ago

Metals in group 2 on the period table most commonly form which type

LuckyWell [14K]

Answer:

alkaline earth metals

Group 2 metals, the alkaline earth metals, have 2 valence electrons, and thus form M2+ ions. The halogens, Group 17 , reach a full valence shell upon reduction, and thus form X− ions

Explanation:

6 0

3 years ago

An airplane wing is designed so that the speed of the air across the top of the wing is 255 m/s when the speed of the air below

grin007 [14]

<h2>Answer:442758.96N</h2>

Explanation:

This problem is solved using Bernoulli's equation.

Let $P$ be the pressure at a point.

Let $p$ be the density fluid at a point.

Let $v$ be the velocity of fluid at a point.

Bernoulli's equation states that $P+\frac{1}{2}pv^{2}+pgh=constant$ for all points.

Lets apply the equation of a point just above the wing and to point just below the wing.

Let $p_{up}$ be the pressure of a point just above the wing.

Let $p_{do}$ be the pressure of a point just below the wing.

Since the aeroplane wing is flat,the heights of both the points are same.

$\frac{1}{2}(1.29)(255)^{2}+p_{up}= \frac{1}{2}(1.29)(199)^{2}+p_{do}$

So, $p_{up}-p_{do}=\frac{1}{2}\times 1.29\times (25424)=16398.48Pa$

Force is given by the product of pressure difference and area.

Given that area is $27ms^{2}$ .

So,lifting force is $16398.48\times 27=442758.96N$

6 0

3 years ago

hooke's law is described mathematically using the formula fsp=-kx. which statement is correct about spring force, fsp? A. It is

bogdanovich [222]

Answer:

A. It is always a positive force

Explanation:

Hooke's law describes the relation between an applied force and extension ability of an elastic material. The law states that provided the elastic limit, e, of a material is not exceeded, the force, F, applied is proportional to the extension, x, provided temperature is constant.

i.e F = - kx

where k is the constant of proportionality, and the minus sign implies that the force is a restoring force.

The applied force can either be compressing or stretching force.

6 0

3 years ago

Can you help me with my homework please ? Science

geniusboy [140]

The formula for average speed is S=D/T

1. S=72m/37s

Divide

S= 1.94

Kira's average speed is 1.94m/s.

2. S=7.5km / 1.5h

S=5

Your average speed is 5km/h

3. S=1260km/3.5h

S=360

The airplanes average speed is 360km/h

7 0

3 years ago