The first thing that needs to be done is to find everything in the same units. 12 hours becomes 43200 seconds. Then find the distance traveled by light in that amount of time. Using the formula v=d/s, manipulate it so it looks like d=v*s. Then plug in the values: d=(3x10^8)*43200, d=1.3x10^13m. But you need to find this in kilometers. To do this, simply divide your answer by one thousand. Thus, a laser beam would travel 1.3x10^10 kilometers in 12 hours.
Answer:
Friction between the box and the floor is 25N to the left.
Explanation:
According to Newton's second law of motion, the net force acting on an object is equal to the produce between the object's mass and its acceleration:
where
m is the mass of the object
a is its acceleration
In this problem, we have two forces acting on the object:
- The applied force, F = 25 N, to the right
- The force of friction 
, opposing the motion of the box, so to the left
So we can write the net force as
Also, we know that the box is moving at constant speed: this means its acceleration is zero, so
Therefore
WHich means:
And therefore,
which means that the force of friction is also 25 N.
Answer:
Explanation:
The sum of the pore along the plane is expressed according to Newton's law
Fn-Ff = ma
Fn is the moving force
Ff = nR = frictional force
m is the Mass
a is the acceleration
Substitute the given values
Fn - nR = ma
Fn - tan31°(mgcostheta) =3.9(9.8)
Fn - tan31(3.9(9.8)cos31) = 3.9(9.8)
Fn - tan31(38.22cos31)= 38.22
Fn - 32.76tan31 = 38.22
Fn-19.68 = 38.22
Fn = 38.22+19.68.
Fn = 57.90N
Hence Fn (moving force) of the inclined block is 57.90
Answer:
B is the best answer for this question
