 Lv 2559 points

# Irene

• ### State the difference in the distances, from each slit to point Y?

How to find it? Thanks

• ### A factory makes a large number of ropes with lengths either 3 m or 5 m. ?

A factory makes a large number of ropes with lengths either 3 m or 5 m. There are four times as many

ropes of length 3 m as there are ropes of length 5 m.

One rope is chosen at random. Find the expectation and variance of its length

The answer for expectation is 3.4 but how to find it?

Thanks

• ### Total distance moved by particle from time t to time (t+100ms)?

A particle in the string oscillates with an amplitude of 13mm. At time t, the particle has zero displacement

How to calculate ‘total distance moved by the particle from time to time (t+100ms)?

• ### Number of proton and neutron?

How to calculate c)?

Thanks

• ### Stationary wave?

Thanks

• ### Phase different and Intensity?

1)Determine the phase difference between the waves.

How to find it?

2)The intensity of wave Y at point P is I.

Determine, in terms of I, the intensity of wave Z

Thanks

• ### The diagram shows a simplified model of a building with four identical heavy floors?

Still thanks

• ### Kinetic energy lost on impact?

Thanks!

• ### Strain energy in tension?

Thank you!

• ### Stationary wave ?

The answer is B but how to solve it?

Could anyone give my some tips to solve this type of question?....

Thank you

• ### What’s the horizontal force exerted by the wall on rod XY?

First, I calculate the length of ZX and I get 0.288675m. I choose Z as pivot and apply the equation clockwise moment equal to anti-clockwise moment which is  0.288675 x F cos 30 = 75(0.5) and I get 150N for the answer. However, the answer is 130N. Anyone knows how to solve it?

Thanks

• ### Relative atomic mass?

Anyone knows how to solve this question?

Thanks

• ### Equilibrium in gas reaction?

At a pressure of 2.00 × 107 Pa, 1.00 moles of nitrogen was mixed with 3.00 moles of hydrogen. The final equilibrium mixture formed contained 0.300mol of ammonia.

Calculate the amounts, in mol, of nitrogen gas and hydrogen gas in the equilibrium mixture.

The answers are 0.850 mol for nitrogen gas and 2.55mol for hydrogen gas but I can't get the asnwer.

This is what I had done:

N2 + 3 H2 <--> 2 NH3

........Initial.....Change......Equilibrium

N2.....1...........+(-0.30)..........0.7 mol

H2.....3..........+3(-0.3).............2.1 mol

NH3...0...........-(-0.3).........     0.3 mol

Are there any mistakes?

• ### Mole fraction?

how to calculate mole fraction?

• ### What’s the magnitude of the charge on the oil doplet?

May I know why’s the answer A instead or B or C?

• ### How many lines per millimetre are on the diffraction grating?

Anyone knows how to calculate?

Physics2 months ago
• • ### How to find most likely number?

Probability that an apple picked at random from a sack is bad is 0.15.

What’s the most likely number of bad apples in a sample of 30 apples?

• ### The function f is defined by f(x)=2x^2+12x+11 for x<=-4?

The function g is defined by g(x)=2x-3 for x<=k

State the largest value of k possible for the composition fg to be defined

fg(x)=8x^2-7

How to solve this question?

Thanks

• 