Answer:
The linear momentum of a particle with mass m moving with velocity v is defined as
p = mv (7.1)
Linear momentum is a vector . When giving the linear momentum of a particle you must
specify its magnitude and direction. We can see from the definition that its units must be
kg·m
s
. Oddly enough, this combination of SI units does not have a commonly–used named so
we leave it as kg·m
s
!
The momentum of a particle is related to the net force on that particle in a simple way;
since the mass of a particle remains constant, if we take the time derivative of a particle’s
momentum we find
dp
dt = m
dv
dt = ma = Fnet
so that
Fnet =
dp
dt (7.2)
 
        
             
        
        
        
Answer:
The element "AI"  has:
Protons: 13 Neutrons: 14 Electrons: 13
Have a great day.
 
        
                    
             
        
        
        
The period of a simple pendulum is given by:

where L is the pendulum length, and g is the gravitational acceleration of the planet. Re-arranging the formula, we get:

 (1)
We already know the length of the pendulum, L=1.38 m, however we need to find its period of oscillation.
We know it makes N=441 oscillations in t=1090 s, therefore its frequency is

And its period is the reciprocal of its frequency:

So now we can use eq.(1) to find the gravitational acceleration of the planet:
 
 
        
        
        
Answer:
minimum length of a surface crack is 18.3 mm
Explanation:
Given data 
plane strain fracture toughness K = 82.4 MPa m1/2
stress σ = 345 MPa 
Y = 1
 
to find out 
the minimum length of a surface crack 
solution
we will calculate length by this formula
length = 1/π ( K / σ Y)²
put all value 
length = 1/π ( K / σ Y)²
length = 1/π ( 82.4  / 345× 1)²
 / 345× 1)²
length = 18.3 mm
minimum length of a surface crack is 18.3 mm