Using the doppler waves simulation set the unshifted wavelength of the light to 415 nm. set the v/c slider to -0.017 and start the simulation, pausing after waves reach the far side of the screen. with the simulation paused use the distance indicator in the simulation to measure the distance between two successive crests along the dotted line to the right of the moving object. this distance is the apparent wavelength of the light λa.

λa =

using the relationship determine your measured v/c v/c (measured with slider at -0.017) = (record your answer to at least 2 significant figures)

now reset the simulation and set the v/c slider to -0.076 and repeat the steps above

v/c (measured with slider at -0.076) = your answer to at least 2 significant figures)

photocells convert light energy to electricity

measuring things 1 litre of water

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.