The fine horizontal scratches etched onto a bullet after it has been fired are called Striations.
<h3>What is Striations?</h3>
- Striations are the minute differences in the curve of the bullet's surface. The bullet and the gun barrel are the harder and softer materials, respectively, in firearms evidence.
- The striations left on the fired bullet are used as a comparison by firearm examiners.
- When a gun is discharged, the bullet blasts down the barrel where it strikes ridges and grooves, spinning and improving shot accuracy.
- These ridges cause striations in the bullet's soft metal by digging into it.
- An examiner analyses these distinctive markings to verify whether a given bullet was shot from a specific firearm.
- A barrel will produce individual markings in addition to a bullet's land and groove impressions as the projectile passes through.
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Answer:
a) a = 2.383 m / s², b) T₂ = 120,617 N
, c) T₃ = 72,957 N
Explanation:
This is an exercise of Newton's second law let's fix a horizontal frame of reference
in this case the mass of the sleds is 30, 20 10 kg from the last to the first, in the first the horizontal force is applied.
a) request the acceleration of the system
we can take the sledges together and write Newton's second law
T = (m₁ + m₂ + m₃) a
a = T / (m₁ + m₂ + m₃)
a = 143 / (10 +20 +30)
a = 2.383 m / s²
b) the tension of the cables we think through cable A between the sledges of 1 and 20 kg
on the sled of m₁ = 10 kg
T - T₂ = m₁ a
in this case T₂ is the cable tension
T₂ = T - m₁ a
T₂ = 143 - 10 2,383
T₂ = 120,617 N
c) The cable tension between the masses of 20 and 30 kg
T₂ - T₃ = m₂ a
T₃ = T₂ -m₂ a
T₃ = 120,617 - 20 2,383
T₃ = 72,957 N
Answer:
1.5 m/s
Explanation:
Momentum is conserved and conservation of momentum is
p₁ + p₂ = p'₁ + p'₂
or
m₁v₁ + m₂v₂ = m₁v'₁ + m₂v'₂
In our problem, after collision v'₁ will be equal to v'₂.
Since objects are identical m₁ = m₂
m(v₁+ v₂) = 2m x v'₁
(2m/s + 1m/s) = 2v'₁
v'₁ = v'₂ = 1.5 m/s
The amount of work done by two boys who apply 200 N of force in an unsuccessful attempt to move a stalled car is 0.
Answer: Option B
<u>Explanation:
</u>
Work done is the measure of work done by someone to push an object from its present position. We can also define work done as the amount of forces needed to move an object from its present position to another position. So the amount of work done is directly proportionate to the product of forces acting on the object and the displacement of the object.

So in this present case, as the two boys have done an unsuccessful attempts to push a stalled car so that means the displacement of the car is zero as there is no change in the position of the car. But they have applied a force of 200 N each. So the amount of work done will be

Thus, the amount of work done by two boys will be zero due to their unsuccessful attempt to move a stalled car.