Answer:
185.25 m/s
Explanation:
consider the motion of the combination of bullet and block after the collision
v₀ = initial speed just after the collision
v' = final speed = 0 m/s
μ = Coefficient of friction = 0.6
g = acceleration due to gravity = 9.8 m/s²
a = acceleration of the combination = - μ g = - (0.6) (9.8) = - 5.88 m/s²
d = stopping distance = 13 m
using the kinematics equation
v'² = v₀² + 2 a d
0² = v₀² + 2 (- 5.88) (13)
v₀ = 12.4 m/s
m = mass of the bullet = 9.9 g = 0.0099 kg
M = mass of the wood = 138 g = 0.138 kg
v = speed of bullet before collision
v₀ = speed of combination after the collision = 12.4 m/s
Using conservation of momentum
m v = (m + M) v₀
(0.0099) v = (0.0099 + 0.138) (12.4)
v = 185.25 m/s
, to hit nails into a piece of wood or a wall, or to break things into pieces.
Answer:
a) 5 N b) 225 N c) 5 N
Explanation:
a) Per Coulomb's Law the repulsive force between 2 equal sign charges, is directly proportional to the product of the charges, and inversely proportional to the square of the distance between them, acting along the line that joins the charges, as follows:
F₁₂ = K Q₁ Q₂ / r₁₂²
So, if we make Q1 = Q1/5, the net effect will be to reduce the force in the same factor, i.e. F₁₂ = 25 N / 5 = 5 N
b) If we reduce the distance, from r, to r/3, as the factor is squared, the net effect will be to increase the force in a factor equal to 3² = 9.
So, we will have F₁₂ = 9. 25 N = 225 N
c) If we make Q2 = 5Q2, the force would be increased 5 times, but if at the same , we increase the distance 5 times, as the factor is squared, the net factor will be 5/25 = 1/5, so we will have:
F₁₂ = 25 N .1/5 = 5 N
<span>The number in front is the number of molecules (or atoms) taking part in the (balanced) chemical reaction equation.</span>
