Answer:
A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newton (N). Force is represented by the symbol F. The original form of Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time.
Other units: dyne, pound-force, poundal, kip, kilopond
SI unit: newton (N)
Common symbols: F→, F, F
The value of the angle of the incline

at which the block starts to slide is the angle at which the component of the weight parallel to the incline becomes equal to the frictional force that keeps the block on the incline:

where the term on the left is the component of the weight parallel to the incline, and the term on the right is the frictional force, which is the product between the coefficient of friction

and the normal reaction of the incline N.
The normal reaction of the incline, N, is equal to the component of the weight perpendicular to the incline:

Therefore, the initial equation becomes

From which we find


For angles above this value, the block will start sliding down, otherwise the block will stay on the incline.
Newton’s 3rd law of motion
Level of sound is related to intensity by this equation

given that
L = 85 dB
also we know that

now we have

By solving above equation


now above is the intensity due to two firecrackers and if we wish to find the sound level of one firecracker then we will find its half level intensity


now again by above formula


Answer:
7 mm per year
Explanation:
It is given that :
The Pacific plate is moving towards north at = 29 mm per year
The Pacific plate is moving towards west at = 20 mm per year
We have to calculate the total relative motion towards the northwest.
So we have to find the resultant of the two motions.
Since the two movements are perpendicular, therefore the angle between the two motions is 90 degree.
Therefore, finding their resultant,


R = 7
Therefore, total relative motion towards the northwest is 7 mm per year.