Answer:
a) v2f = 1.2 m/s, b) h = 7.35 10⁻² m and c) ΔK = -4196.4 J
,
Explanation:
a) This problem must be solved with the conservation of the moment. Let's define the system as the one formed by the bullet plus the block, in this system all the forces are internal therefore the moment conserves, let's write the moment in two moments before and after the crash. In general these shocks are very fast, so it can be assumed that the box does not move during the crash.
The data they give us is the mass of the bullet (m = 0.010 kg), the initial and final velocities of the bullet (v1o = 1000 m / s and v1f = 400 m / s) and the block gives us the mass M = 5 kg and its initial velocity v2o = 0 m / s
Before the crash
po = m v₁₀
After the crash
pf = m + M
p₀ = pf
m v₁₀ = m + M
v2f = m (v₁₀ - ) / M
v2f = 0.010 (1000-400) / 5
v2f = 1.2 m / s
b) Having the speed of the block we can use the law of conservation of energy to find the height. Let's write the mechanical energy of the block just after the crash and at the point of maximum height
Initial. Just after the crash
v =
Em1 = K = ½ M v²
Final. At maximum height
Em₂ = U = M g h
Em₁ = Em₂
½ M v² = M g h
h = ½ v² / g
h = ½ 1.2² / 9.8
h = 0.0735 m
h = 7.35 10⁻² m
c) Let's calculate the kinetic energy before and after the crash
Before
K₀ = ½ m v₁₀²
K₀ = ½ 0.01 1000²
K₀ = 5000 J
Final
= ½ m v1f² + ½ M v2f²
= ½ 0.010 400² + ½ 5 1.2²
= 800 + 3.6
= 803.6 J
We can give the amount of energy that is lost as the subtraction of the two energies or as the fraction of lost engoa
ΔK = -K₀
ΔK = 803.6 - 5000
ΔK = -4196.4 J
/ K₀ = 803.6 / 5000
/ K₀ = 0.16
Examples<span> of </span>reversible changes<span> include melting chocolate and </span>changing<span> it back into a solid by cooling it, and melting candle wax by heating it and solidifying the wax by cooling it. </span>Reversible changes<span> are </span>changes<span> that can be reversed. They are also known as </span>physical changes<span>.</span>
I need a pic so I can give you an answer
During a car crash, the car decelerates extremely rapidly, so inertia causes you to move forward quickly. If there wasn't an airbag to slow you down, you might fly out the windshield.
The air bag increases impulse by increasing the time during which a force acts on you (impulse=force*time). This decreases your forward momentum, so you'll have a better chance of surviving.
Answer:
Therefore the ratio of diameter of the copper to that of the tungsten is
Explanation:
Resistance: Resistance is defined to the ratio of voltage to the electricity.
The resistance of a wire is
- directly proportional to its length i.e
- inversely proportional to its cross section area i.e
Therefore
ρ is the resistivity.
The unit of resistance is ohm (Ω).
The resistivity of copper(ρ₁) is 1.68×10⁻⁸ ohm-m
The resistivity of tungsten(ρ₂) is 5.6×10⁻⁸ ohm-m
For copper:
......(1)
Again for tungsten:
........(2)
Given that and
Dividing the equation (1) and (2)
[since and ]
Therefore the ratio of diameter of the copper to that of the tungsten is