Given :
The ball of a ballpoint pen is 0.5 mm in diameter and has an ASTM grain size of 12.
To Find :
How many grains are there in the ball?
Solution :
Volume of ball of the ballpoint is :

Now, grain size of 12 has about 520000 grains/mm³.
Therefore, number of grains are :

Answer:
- The initial speed of the truck is 21.93 m/s, and the initial speed of the car is 19.524 m/s
Explanation:
We can use conservation of momentum to find the initial velocities.
Taking the unit vector
pointing north and
pointing east, the final velocity will be


The final linear momentum will be:




As there are not external forces, the total linear momentum must be constant.
So:

As initially the car is travelling east, and the truck is travelling north, the initial linear momentum must be
so:
so

So, for the truck





And, for the car



health conditions and diseases
Newton's second law allows calculating the response for the person's acceleration while leaving the trampoline is:
-4.8 m / s²
Newton's second law says that the net force is proportional to the product of the mass and the acceleration of the body
F = m a
Where the bold letters indicate vectors, F is the force, m the masses and the acceleration
The free body diagram is a diagram of the forces without the details of the body, in the attached we can see the free body diagram for this system
-W = m a
Whera
is the trampoline force
Body weight is
W = mg
We substitute
- mg = ma
a =
Let's calculate
a = 
a = -4.8 m / s²
The negative sign indicates that the acceleration is directed downward.
In conclusion using Newton's second law we can calculate the acceleration of the person while leaving the trampoline is
-4.8 m / s²
Learn more here: brainly.com/question/19860811
Explanation:
A pilot flying a weight; it takes t = 3.4 s to hit the ground, during which it travels a horizontal distance d = 120 m
h = g/2*t^2
h= 4.903*3.4^2
h=56.701 m
V = d/t
V= 120/3.4
V=35.3 m/sec
Now the pilot does a run at the same height but twice the speed.
How much time (t1) does it take the weight to hit the ground?
t1 = t = 3.4 sec (depending just upon height)