Answer:
t=0.42s
Explanation:
Here you have an inelastic collision. By the conservation of the momentum you have:

m1: mass of the bullet
m2: wooden block mass
v1: velocity of the bullet
v2: velocity of the wooden block
v: velocity of bullet and wooden block after the collision.
By noticing that after the collision, both objects reach the same height from where the wooden block was dropped, you can assume that v is equal to the negative of v2. In other words:

Where you assumed that the negative direction is upward. By replacing and doing v2 the subject of the formula you get:

Now, with this information you can use the equation for the final speed of an accelerated motion and doing t the subject of the formula. IN other words:

hence, the time is t=0.42 s
Answer:
The acceleration would be 3.455.
Answer:
life (N) of the specimen is 117000 cycles
Explanation:
given data
ultimate strength Su = 120 kpsi
stress amplitude σa = 70 kpsi
solution
we first calculate the endurance limit of specimen Se i.e
Se = 0.5× Su .............1
Se = 0.5 × 120
Se = 60 kpsi
and we know strength of friction f = 0.82
and we take endurance limit Se is = 60 kpsi
so here coefficient value (a) will be
a =
......................1
put here value and we get
a =
a = 161.4 kpsi
so coefficient value (b) will be
b =
b =
b = −0.0716
so here number of cycle N will be
N = 
put here value and we get
N = 
N = 117000
so life (N) of the specimen is 117000 cycles
Do you have any answer options?
The most I can help is to tell you that a covalent bond is a type of bond that shares electrons between the bonded atoms.
The answer would be 54 m/s as the maximum speed