Answer:
a) 8.80 N
b) 4.78 N
Explanation:
The weight of the book is
By Newton's third law, the reaction from the table, R, is equal to its weight.
R = 19.9143 N
From the law of solid friction,
F is the maximum frictional force and 
is the coefficient of friction.
a) The force needed to begin moving the book is that needed to overcome static friction
b) The force needed to move the book at constant speed once it begins moving is that needed to overcome kinetic friction
<span>Murphy's law is an adage or epigram that is typically stated as: Anything that can go wrong, will go wrong.
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Answer:
2.The density of air increases and thendecreases as the sound wave passes.
Explanation:
Sound waves are mechanical waves, which consist of oscillation of the particles in the medium where the wave is transmitted through.
Sound waves are also longitudinal waves, which means that the direction of oscillations of the particles of the medium occurs in a direction parallel to the direction of motion of the wave (so, essentially back and forth).
Due to the nature of longitudinal waves, they create alternating regions of the medium where the density of particles are higher and lower. The former are called compressions, while the latter are called rarefactions.
Therefore, when a sound wave travels through the air, the density of one region of air continuously changes: compression first (high density), rarefaction then (lower density), then compression again, etc..
Answer:
<u>Average Velocity:</u>
When a body covers some displacement moving from point A to B, in a given time,t. Then dividing the total distance covered by the time taken to complete the displacement is called as the average velocity of that car.
We can calculate the average velocity of car by subtracting the initial displacement of a body,s₁ from the final displacement position of the body, s₂. And then dividing by the initial time,t₁ been subtracted from the final time,t₂.
We will get the required results, now if we want to obtain the results in the final three seconds then, we can have the following explanation to that as given.
Explanation:
Lets say, that we have the car moving for 10 seconds and then it stops at the eleventh second of the trip on final position, of the displacement. Then we divide the whole trips into small segments, as we will have the different velocity at each interval but, the velocity is unknown at the last 3 seconds is unknown=?.
- Total time taken, Δt= 11 seconds,
- Then lets say the velocity at the 8th second is , v=25 m/s,then
- Δv=x₂-(25)/11-0,⇒Δv=x₂-25/11,
Answer:
304.89m
Explanation:
Given
acceleration a = 2.52m/s²
final speed v = 39.2m/s
initial speed = 0m/s (car accelerates from rest)
Using the equation of motion below to get the distance of Doc brown from Marty;
v² = u²+2as
substitute the given parameters
39.2² = 0²+2(2.52)s
1536.64 = 0+5.04s
divide both sides by 5.04
1536.64/5.04 = 5.04s/5.04
rearrange the equation
5.04s/5.04 = 1536.64/5.04
s = 304.89m
Hence He and Marty must stand at 304.89m to allow the car to accelerate from rest to a speed of 39.2 m/s?
