Answer:
W = 18.88 J
Explanation:
Given that,
Constant force, F = 11.8 N (in +x direction)
Mass of an object, m = 4.7 kg
The object moves from the origin to the point (1.6i – 4.6j) m
We need to find the work is done by the given force during this displacement. The work done by an object is given by the formula as follows :

So, the work done by the given force is 18.88 J.
Answer:
Red light
Explanation:
The energy emitted during an electron transition in an atom of hydrogen is given by

where
is the energy of the lowest level
n1 and n2 are the numbers corresponding to the two levels
Here we have
n1 = 3
n2 = 2
So the energy of the emitted photon is

Converting into Joules,

And now we can find the wavelength of the emitted photon by using the equation

where h is the Planck constant and c is the speed of light. Solving for
,

And this wavelength corresponds to red light.
The correct answer to this question is D
Answer:
75.36 mph
Explanation:
The distance between the other car and the intersection is,
The distance between the police car and the intersection is,
(Negative sign indicates that he is moving towards the intersection)
Therefore the distance between them is given by,
The rate of change is,
Now finding
when
from (1) we have
The officer's radar gun indicates 25 mph pointed at the other car then,
when
from
From (2) we get
Hence the speed of the car is 