Answer:
d = 0.544 m
Explanation:
To solve this problem we must work in two parts: one when the surface has no friction and the other when the surface has friction
Let's start with the part without rubbing, let's find the speed that the box reaches., For this we use the conservation of mechanical energy in two points: maximum compression and when the box is free (spring without compression)
Initial, maximum compression
Em₀ = Ke = ½ k x²
Final, free box without compressing the spring
= K = ½ m v²
Emo =
½ k x² = ½ m v²
v = √ (k / m) x
Let's reduce the SI units measures
x = 20 cm (1m / 100cm) = 0.20 m
v = √ (100 / 2.5) 0.20
v = 1,265 m / s
Let's work the second part, where there is friction. In this part the work of the friction force is equal to the change of mechanical energy
= ΔEm = - Em₀
= - fr d
Final point. Stopped box
= 0
Starting point, starting the rough surface
Em₀ = K = ½ m v²
With Newton's second law we find the force of friction
fr = μ N
N-W = 0
N = W = mg
fr = μ mg
-μ m g d = 0 - ½ m v²
d = ½ v² / (μ g)
Let's calculate
d = ½ 1,265² / (0.15 9.8)
d = 0.544 m
Answer:
I would say a pond
Explanation:
A pond is more still than an ocean, therefore you could see your reflection better
Answer:
C) equal to zero
Explanation:
Electric potential is calculated by multiplying constant and charge, then dividing it by distance. The location that we want to measure is equidistant from two particles, mean that the distance from both particles is the same(r2=r1). The charges of the particle have equal strength of magnitude but the opposite sign(q2=-q1). The resultant will be:V = kq/r
ΔV= V1 + V2= kq1/r1 + kq2/r2
ΔV= V1 + V2= kq1/r1 + k(-q1)/(r)1
ΔV= kq1/r1 - kq1/r1
ΔV=0
The electric potential equal to zero
Answer: hello your question is incomplete below is the missing part
A 69-kg petty thief wants to escape from a third-story jail window. Unfortunately, a makeshift rope made of sheets tied together can support a mass of only 58 kg.
answer:
To 2 significant Figures = 1.6 m/s^2
Explanation:
<u>Calculate the magnitude of minimum acceleration at which the thief can descend </u>
we apply the relation below
Mg - T = Ma --- ( 1 )
M = 69kg
g = 9.81
T = 58 * 9.81
a = ? ( magnitude of minimum acceleration)
From equation 1
a = [ ( 69 * 9.81 ) - ( 58 * 9.81 ) ] / 69
= 1.5639 m/s^2
To 2 significant Figures = 1.6 m/s^2
Answer:
f (frequency) = V / y where V is the speed of sound and y the wavelength
f = 1500 m/s / 1.5 m = 1000 / sec
T (period) = 1 / f = .001 sec
Suppose you replace the horn by a drum then the period would be the time between the beats of the drum - now if the source is moving towards the observer then the distance between crests of the wave produced by the drum will be shortened by V * T because of the motion of the drum "towards" the observer, and since the wavelength is shorter the frequency heard by the observer will be higher, and the higher the speed of of the car the shorter the wavelength as seen by the observer and the higher the frequency.
Also, if the car is moving away from the observer then the distance between the crests of the wave emitted will be further apart, and the observer will hear a lower frequency.
