As a killer whale swims toward a seal, it sends out sound waves to determine the direction the seal is moving. When the

Which type of thermal energy transfer does a wrapping of cotton or plastic reduce the most, conduction, convection, radiation, t

Veseljchak [2.6K]

Answer: Thermal Energy is energy resulting from the motion of particles; It is a form of kinetic energy and is transferred as heat; Thermal Energy Transfer can occur by three methods: Conduction; Convection; Radiation; Conduction. Conduction is the transfer of thermal energy through direct contact between . particles of a substance.

Explanation:

8 0

3 years ago

You are standing on a sheet of ice that covers the football stadium parking lot in Buffalo; there is negligible friction between

Anni [7]

Answer:

0.074m/s

Explanation:

We need the formula for conservation of momentum in a collision, this equation is given by,

$m_1u_1+m_2u_2 = m_1v_1+m_2v_2$

Where,

$m_1$ = mass of ball

$m_2$ = mass of the person

$u_1$ = Velocity of ball before collision

$u_2$ = Velocity of the person before collision

$v_1$ = velocity of ball afer collision

$v_2$ = velocity of the person after collision

We know that after the collision, as the person as the ball have both the same velocity, then,

$v_1 = v_2$

$m_1u_1 + m_2u_2 = (m_1+m_2)v_2$

Re-arrenge to find $v_2$ ,

$v_2 = \frac{m_1u_1+m_2u_2}{m_1+m_2}$

Our values are,

$m_1$ = 0.425kg

$u_1$ = 12m/s

$m_2$ = 68.5kg

$u_2$ = 0m/s

Substituting,

$v_2 = \frac{(0.425)(12)+(68.5)(0)}{0.425+68.5}$

$v_2 = 0.074m/s$

The speed of the person would be 0.074m/s after the collision between him/her and the ball

7 0

3 years ago

5. Which of these is necessary for electricity to flow?

CaHeK987 [17]

Answer:

the circuit must be closed

Explanation:

4 0

3 years ago

Read 2 more answers

The kitchen in your house measures 10 ft by 10 ft. You need to have 50 footcandles of illumination in the room. How many 60 watt

tekilochka [14]

Answer:

6 bulbs are needed to illuminate the room.

Explanation:

Given:

Measurement of kitchen (A) = 10 ft by 10 ft = 100 sq. ft

Number of footcandles (n) = 50

Lumens emitted by 1 bulb = 834

Number of bulbs (N) = ?

We are also given,

1 foot candle = 1 lumen/sq. ft

So, 50 foot candles = 50 lumens/sq. ft

Now, for an area of 1 sq. ft 50 lumens are emitted.

So, for an area of 100 sq. ft, lumens emitted = 50 × 100 = 5000 lumens

Now, one bulb emits = 834 lumes

Therefore, number of bulbs required for emitting 5000 lumens is given as:

$N=\frac{Number\ of\ lumens}{Number\ of\ lumens\ by\ 1\ bulb}\\\\N=\frac{5000}{834}=5.995\approx6$

So, 6 bulbs are needed to illuminate the room.

7 0

3 years ago

A farsighted boy has a near point at 2.3 m and requires eyeglasses to correct his vision. Corrective lenses are available in inc

tino4ka555 [31]

Answer:

P = 3.5 D

Explanation:

As we know that convex lens is to be used to make the near point of eye to be correct

So we will have

$\frac{1}{d_i} + \frac{1}{d_o} = \frac{1}{f}$

here we have

$d_i = 2.3 m = 230 cm$

$d_o = 25 cm$

now plug in all values into the formula

$-\frac{1}{230} + \frac{1}{25} = \frac{1}{f}$

$f = 28 cm$

now for power of lens

$P = \frac{1}{f}$

$P = \frac{1}{0.28} = 3.5 D$

so the power in dioptre is

P = 3.5 D

5 0

2 years ago