A train travels 77 kilometers in 4 hours, and then 76 kilometers in 2 hours. What is its average speed?

A 57.0 kg cheerleader uses an oil-filled hydraulic lift to hold four 120 kg football players at a height of 1.10 m. If her pisto

lapo4ka [179]

Answer:

The diameter of the piston of the players equals 55.136 cm.

Explanation:

from the principle of transmission of pressure in a hydraulic lift we have

$\frac{F_{1}}{A_{1}}=\frac{F_{2}}{A_{1}}$

Since the force in the question is the weight of the individuals thus upon putting the values in the above equation we get

$\frac{57.0\times 9.81}{\frac{\pi \times (19.0)^{2}}{4}}=\frac{4\times 120\times 9.81}{\frac{\pi \times D_{2}^{2}}{4}}$

Solving for $D_{2}$ we get

$D_{2}^{2}=\frac{4\times 120}{57}\times 19^{2}\\\\\therefore D_{2}=\sqrt{\frac{4\times 120}{57}}\times 19\\\\D_{2}=55.136cm$

5 0

3 years ago

What do we mean when we say that two light rays striking a screen are in phase with each other? What do we mean when we say that

galina1969 [7]

Answer: When the electric field due to one is a maximum, the electric field due to the other is also a maximum, and this relation is maintained as time passes. They alternatively reinforce and cancel each other.

Explanation:

In a wave, the phase, is an arbitrary time reference, used to locate a given point of the wave in time, within a cycle.

Two waves can travel at the same speed, or even have the same wavelength, but this is not enough to be sure that at a given point in time, both waves will be in their maximum, as it only can be determined from the phase of the waves.

So, only when the waves reach at the same point in time at the same amplitude, we can say that they arrive in phase, in a constructive interference.

8 0

2 years ago

A child whirls a ball in a vertical circle. Assuming the speed of the ball is constant (an approximation), when would the tensio

BARSIC [14]

Answer:

C. At the bottom of the circle.

Explanation:

Lets take

Radius of the circle = r

Mass = m

Tension = T

Angular speed = ω

The radial acceleration towards = a

a= ω² r

Weight due to gravity = mg

<h3>At the bottom condition</h3>

T - m g = m a

T = m ω² r + m g

<h3>At the top condition</h3>

T + m g = m a

T= m ω² r -m g

From above equation we can say that tension is grater when ball at bottom of the vertical circle.

Therefore the answer is C.

C. At the bottom of the circle.

8 0

2 years ago

PLEASE ANSWER ASAP!! YOU WILL GET BRAINLIEST IF RIGHT!

Elena-2011 [213]

D just east of station b

6 0

2 years ago

Read 2 more answers

At a certain distance from a point charge, the potential and electric-field magnitude due to that charge are 4.98 V and 16.2 V/m

son4ous [18]

Answer:

A. 30.7cm

B. $1.7*10^{-10}C$

C. The electric field is directed away from the point of charge

Explanation:

A.

$because, E=\frac{v}{d} \\\\d= \frac{4.98}{16.2}\\\\ d = 0.307m\\\\d = 30.7 cm$

B.

Considering Gauss's law

$EA = \frac{Q}{e}\\\\ where, e = pertittivity. space= 8.85* 10^{-12} Fm^{-1} \\\\A = surface. area. with.radius 0.307m\\Q= eEA = (8.85*10^{-12})(16.2)(4\pi)(0.307)^{2}\\\\= 1.7*10^{-10}C$

C. The electric field directed away from the point of charge when the charge is positive.

3 0

3 years ago