Answer:
a) K = 49.5 J b) k = 1378 N / m c) ΔE = 34 J d) μ = 0.399
Explanation:
For this exercise we will use the concepts of energy
a) The initial kinetic energy is
K = ½ m v²
K = ½ 3.96 5²
K = 49.5 J
b) let's use energy conservation
Em₀ = K = ½ m v²
= Ke = ½ k x²
Em₀ =
½ m v² = ½ k x²
k = m v² / x²
k = 3.96 5² / 0.268²
k = 1378 N / m
c) Let's calculate the final energy of the spring
= Ke = ½ k x²
= ½ 1378 0.15²
= 15.5 J
The initial energy is the kinetics of the block
Em₀ = 49.5 J
The lost energy is the difference with the initial
ΔE = - Em₀
ΔE = 15.5 - 49.5
ΔE = - 34 J
the negative sign means that the energy dissipates
d) For this part we use the concept of work
W = F d cos θ = ΔK
In this case the force is the friction force that always opposes displacement, so the angle 180 ° and cos 180 = -1
W = -fr d = ΔK
The force of friction is
fr = μ N
With Newton's second law
N-w = 0
N = W = mg
Let's calculate
-μ mg d = Kf -K₀o
μ = K₀ / mgd
μ = 49.5 / (3.96 9.8 3.20)
μ = 0.399
Answer:
Explanation:
Let us first calculate for Virgo
Using Hubble's law
For Virgo
Percentage difference for the Virgo
Now for calculate for Corona Borealis
Using Hubble's law
For Corona Borealis
Percentage difference for the Virgo
So clearly Hubble's law is more accurate for the closer objects
Answer:
-26 m/s (backward)
Explanation:
We can solve this problem by using the law of conservation of momentum.
In fact, the total momentum momentum of the cannon + ball system must be conserved before and after the explosion.
Before the explosion, they are both at rest, so the total momentum is zero:
p = 0
After the explosion, the total momentum is:
where
M = 1.5 kg is the mass of the cannon
m = 0.52 kg is the mass of the ball
v = +75 m/s is the velocity of the ball
V is the velocity of the cannon
Since the momentum is conserved, we can equate the two expressions:
And solving, we find V:
where the negative sign means the direction is opposite to that of the ball.