Question:A bullet traveling horizontally at a speed of 350 m/s hits a board perpendicular to the surface, passes through it, and emerges on the other side at a speed of 210 m/s. If the board is 4.00 cm thick, how long does the bullet take to pass through it?
Answer #1: Using one of the equation of motion:
s = ½(𝑣+𝑢)t
t = 2sv+u2s𝑣+𝑢
t = 2∗0.04210+3502∗0.04210+350
t ≈ 1.43 x 10¯⁴ s or 143 μs ← time bullet will take to pass through the 4.00 cm board
A paper showing question: a bullet traveling horizontally at a speed of 350
Answer #2: take the average of the two speeds: 350 + 210 = 560
560 /2 = 280m/s thats equivalent to 28,000 cm/s
so it at that average speed through wood it covers 28,000 cm in 1 second
4 cm will be traveled in 4/28,000 seconds, or 1/7,000 of a second.
The method to solve the above question is through equations of motion. Let's learn about them.
Equations of motion in physics are equations that explain how a physical system behaves in terms of how its motion changes over time.
The behavior of a physical system is described in more detail by the equations of motion as a collection of mathematical functions expressed in terms of dynamic variables.
The fundamental equation of motion in classical mechanics is Newton's second law, which states that the force F acting on a body is equal to that body's mass m times its center of mass's acceleration a, or F = ma.
One kinematic variable is described as a function of time in each of the first two equations of motion. Simply put... When acceleration is constant, velocity is directly proportional to time (v ∝ t)). When acceleration is constant, displacement is proportional to time squared (∆s ∝ t2).
The components such as displacement (s), velocity (initial and final), time (t), and acceleration are derived with the help of these equations (a).
Therefore, they can only be utilized in situations in which the acceleration is unchanged and the path of motion is linear.
- It only works during free fall.
- It functions only in ideal conditions.
- Air resistance and friction are of little concern to it.
The three equations are, v = u + at. v² = u² + 2as. s = ut + ½at²
Every object in a condition of uniform motion will remain in that state unless an external force is given to it, according to the first of Isaac Newton's (1642–1726) three laws of motion, which he articulated in the 17th century. This is essentially a restatement of Galileo's concept of inertia.
The first equation of motion is v = u +at. Here, v is the final velocity, u is the initial velocity, a is the acceleration and t is the time.
Above are the two answers to the question of a bullet traveling horizontally at a speed of 350 m/s. Hope you find them helpful.