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Ainat [17]
3 years ago
5

 Find the average acceleration of a northbound subway train that slows down from 12 m/s to 9.6 m/s in 0.8 seconds.​

Physics
1 answer:
iren2701 [21]3 years ago
8 0

Answer:

a=-3\ m/s^2

Explanation:

Given that,

Initial speed of a train, u = 12 m/s

Final speed of a train, v = 9.6 m/s

Time taken, t = 0.8 s

We need to find the average acceleration of the train. We know that the rate of change of velocity is equal to acceleration. So,

a=\dfrac{v-u}{t}\\\\a=\dfrac{9.6-12}{0.8}\\\\a=-3\ m/s^2

So, the average acceleration of the train is equal to -3\ m/s^2.

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A particle in circular motion performs 30 oscillation in 6 seconds. what is it angular velocity​
sp2606 [1]

Explanation:

ω = 30 rev × (2π rad/rev) / (6 sec)

ω = 10π rad/s

ω ≈ 31.4 rad/s

4 0
4 years ago
A train of mass 320000 kg accelerate uniformly from rest. It takes 57 s to travel a distance of 810 m in a straight line. Find t
Nastasia [14]

Answer:

160,000 N

Explanation:

Given:

m = 320,000 kg

v₀ = 0 m/s

a = constant

t = 57 s

Δx = 810 m

Find: Fnet

Apply Newton's second law:

∑F = ma

Fnet = ma

To find Fnet, we must first find the acceleration.

x = x₀ + v₀ t + ½ at²

810 m = 0 m + (0 m/s) (57 s) + ½ a (57 s)²

a = 0.50 m/s²

Fnet = (320,000 kg) (0.50 m/s²)

Fnet = 160,000 N

8 0
4 years ago
What are the three most influential variables that affect electrical force?
snow_tiger [21]
I know that the answer is 3 because 1+2 is 3
4 0
4 years ago
I know the acceleration due to gravity (ie 9.8 m/s2) will have a negative sign when falling down, a positive one when going up.
rewona [7]

Answer:

Yes

Explanation:

Accerelation is measured by change in velocity. So naturally, if an object is slowing down, its velocity is decreasing so acceleration is negative. If it is speeding up velocity is increasing so positive acceleration.

(Velocity final - Velocity initial)/t

Note that this does not apply only to gravity, but to all linear accelerations

6 0
2 years ago
A block of mass M=10 kg is on a frictionless surface as shown in the photo attached. And it's attached to a wall by two springs
nordsb [41]

a.

  • i. the speed of the block of mass when the springs are connected in parallel is 7.07 A m/s
  • ii. the angular velocity when the two springs are in parallel is 7.07 rad/s

b.

  • i. the speed of the block of mass when the springs are connected in series is 11.2 A m/s
  • ii. the angular velocity when the two springs are in series is 11.2 rad/s

<h3>a. </h3><h3>i. How to calculate the velocity of the mass when the springs are connected in parallel?</h3>

Since k is the spring constant of both springs = 250 N/m. The equivalent spring constant in parallel is k' = k + k

= 2k

= 2 × 250 N/m

= 500 N/m

Now since A is the maximum distance the block is pulled from its equilibrium position, the total energy of the block is E = 1/2kA

Also, 1/2k'A² = 1/2k'x² + 1/2Mv² where

  • k' = equivalent spring constant in parallel = 500 N/m,
  • A = maximum displacement of spring,
  • x = equilibrium position = 0 m,
  • M = mass of block = 10 kg and
  • v = speed of block at equilibrium position

Making v subject of the formula, we have

v = √[k'(A² - x²)/M]

Substituting the values of the variables into the equation, we have

v = √[k'(A² - x²)/M]

v = √[500 N/m(A² - (0)²)/10]

v = √[50 N/m(A² - 0)]

v = [√50]A m/s

v = [5√2] A m/s

v = 7.07 A m/s

So, the speed of the block of mass when the springs are connected in parallel is 7.07 A m/s

<h3>ii. The angular velocity of mass when the springs are in parallel</h3>

Since velocity of spring v = ω√(A² - x²) where

  • ω = angular velocity of spring,
  • A = maximum displacement of spring and
  • x = equilbrium position of spring = 0 m

Making ω subject of the formula, we have

ω = v/√(A² - x²)

Since v = 7.07 A m/s

Substituting the values of the other variables into the equation, we have

ω = v/√(A² - x²)

ω = 7.07 A m/s/√(A² - 0²)

ω = 7.07 A m/s/√(A² - 0)

ω = 7.07 A m/s/√A²

ω = 7.07 A m/s/A m

ω = 7.07 rad/s

So, the angular velocity when the two springs are in parallel is 7.07 rad/s

<h3>b. </h3><h3>i. How to calculate the velocity of the mass when the springs are connected in series?</h3>

Since k is the spring constant of both springs = 250 N/m. The equivalent spring constant in parallel is 1/k" = 1/k + 1/k

= 2/k

⇒ k" = k/2

k" = 250 N/m ÷ 2

= 125 N/m

Now since A is the maximum distance the block is pulled from its equilibrium position, the total energy of the block is E = 1/2kA

Also, 1/2k"A² = 1/2k"x² + 1/2Mv'² where

  • k" = equivalent spring constant in series = 125 N/m,
  • A = maximum displacement of spring,
  • x = equilibrium position = 0 m,
  • M = mass of block = 10 kg and
  • v' = speed of block at equilibrium position

Making v subject of the formula, we have

v = √[k"(A² - x²)/M]

Substituting the values of the variables into the equation, we have

v = √[k"(A² - x²)/M]

v = √[125 N/m(A² - (0)²)/10]

v = √[125 N/m(A² - 0)]

v = [√125]A m/s

v = [5√5] A m/s

v = 11.2 A m/s

So, the speed of the block of mass when the springs are connected in series is 11.2 A m/s

<h3>ii. The angular velocity of the mass when the springs are in series</h3>

Since velocity of spring v = ω√(A² - x²) where

  • ω = angular velocity of spring,
  • A = maximum displacement of spring and
  • x = equilbrium position of spring = 0 m

Making ω subject of the formula, we have

ω = v/√(A² - x²)

Since v = 11.2 A m/s

Substituting the values of the other variables into the equation, we have

ω = v/√(A² - x²)

ω = 11.2 A m/s/√(A² - 0²)

ω = 11.2 A m/s/√(A² - 0)

ω = 11.2 A m/s/√A²

ω = 11.2 A m/s/A m

ω = 11.2 rad/s

So, the angular velocity when the two springs are in series is 11.2 rad/s

Learn more about speed of block of mass here:

brainly.com/question/21521118

#SPJ1

3 0
2 years ago
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