Answer:
<em>The coefficient of static friction between the crate and the floor is 0.41</em>
Explanation:
<u>Friction Force</u>
When an object is moving and encounters friction in the air or rough surfaces, it loses acceleration and velocity because the friction force opposes motion.
The friction force when an object is moving on a horizontal surface is calculated by:
[1]
Where
is the coefficient of static or kinetics friction and N is the normal force.
If no forces other then the weight and the normal are acting upon the y-direction, then the weight and the normal are equal in magnitude:
N = W = m.g
The crate of m=20 Kg has a weight of:
W = 20*9.8
W = 196 N
The normal force is also N=196 N
We can find the coefficient of static friction by solving [1] for
:

The friction force is equal to the minimum force required to start moving the object on the floor, thus Fr=80 N and:


The coefficient of static friction between the crate and the floor is 0.41
Answer:
0.001 s
Explanation:
The force applied on an object is equal to the rate of change of momentum of the object:

where
F is the force applied
is the change in momentum
is the time interval
The change in momentum can be written as

where
m is the mass
v is the final velocity
u is the initial velocity
So the original equation can be written as

In this problem:
m = 5 kg is the mass of the fist
u = 9 m/s is the initial velocity
v = 0 is the final velocity
F = -45,000 N is the force applied (negative because its direction is opposite to the motion)
Therefore, we can re-arrange the equation to solve for the time:

Answer:
Explanation:
Polar coordinates formula
Summary. To convert from Polar Coordinates (r,θ) to Cartesian Coordinates (x,y) : x = r × cos( θ ) y = r × sin( θ )
C. The bowling ball and the bicycle
p = mv
P of bike = 12x5 = 60
P of rock = 2x20 = 40
P of ball = 5 x 10 = 60