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2 years ago

A pillow is thrown downward with an initial speed of 6 m/s.

Physics

1 answer:

Yuri [45]2 years ago

8 0

Given :

Initial velocity, u = -6 m/s.

Time taken, t = 4 seconds.

Acceleration due to gravity, $g = -9.8\ m/s^2$ .( Here negative sign means downward direction )

To Find :

Velocity after 4 seconds.

Solution :

By equation of motion.

v = u + at

Here , a = g.

v = u + gt

v = -6 + (-9.8)×4

v = -6 + (-39.2)

v = -45.2 m/s

Therefore, velocity after 4 seconds is -45.2 m/s.

Hence, this is the required solution.

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"if a stream flow measures 12 meters in 60 seconds, what is the stream's average rate of flow?"

Vlad [161]

Discharge is the volume of water moving down a stream or river per unit of time, commonly expressed in cubic feet per second or gallons per day. In general, river discharge is computed by multiplying the area of water in a channel cross section by the average velocity of the water in that cross section: discharge = area * velocity. In this case, the answer is 0.2 m/s.

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2 years ago

Exercise 2.4.6: Suppose you wish to measure the friction a mass of 0.1 kg experiences as it slides along a floor (you wish to fi

JulijaS [17]

Answer:

b = 0.6487 kg / s

Explanation:

In an oscillatory motion, friction is proportional to speed,

fr = - b v

where b is the coefficient of friction

when solving the equation the angular velocity has the form

w² = k / m - (b / 2m)²

In this exercise we are given the angular velocity w = 1Hz, the mass of the body m = 0.1 kg, and the spring constant k = 5 N / m. Therefore we can disperse the coefficient of friction

let's call

w₀² = k / m

w² = w₀² - b² / 4m²

b² = (w₀² -w²) 4 m²

Let's find the angular velocities

w₀² = 5 / 0.1

w₀² = 50

w = 2π f

w = 2π 1

w = 6.2832 rad / s

we subtitute

b² = (50 - 6.2832²) 4 0.1²

b = √ 0.42086

b = 0.6487 kg / s

8 0

2 years ago

The table shows information about four students who are running around a track. Which statement is supported by the information

Vikentia [17]

Answer:

Correct option: Mohammed has less kinetic energy than Autumn.

Explanation:

Kinetic Energy

Is the energy an object has due to its motion. If the object has a mass m and travels at a speed v, then the kinetic energy K is:

$\displaystyle K=\frac{1}{2}mv^2$

The information about four students includes their mass and velocity as follows:

Autumn has a mass of m1=50 kg and a velocity (magnitude) of v1=4 m/s, thus their kinetic energy is:

$\displaystyle K_1=\frac{1}{2}50\cdot 4^2$

$K_1=400\ J$

Mohammed has a mass of m2=57 kg and a velocity (magnitude) of v2=3 m/s, thus their kinetic energy is:

$\displaystyle K_2=\frac{1}{2}57\cdot 3^2$

$K_2=256.5\ J$

Lexy has a mass of m3=53 kg and a velocity (magnitude) of v3=2 m/s, thus their kinetic energy is:

$\displaystyle K_3=\frac{1}{2}53\cdot 2^2$

$K_3=106\ J$

Chiang has a mass of m4=64 kg and a velocity (magnitude) of v4=5 m/s, thus their kinetic energy is:

$\displaystyle K_4=\frac{1}{2}64\cdot 5^2$

$K_4=800\ J$

Sorted from lower kinetic energy to higher:

Lexy, Mohammed, Autumn, Chiang. Thus:

Autumn has more kinetic energy than Chiang. False

Mohammed has less kinetic energy than Autumn. True

Lexy has more kinetic energy than Mohammed. False

Chiang has less kinetic energy than Lexy. False

Correct option: Mohammed has less kinetic energy than Autumn.

3 0

2 years ago

Read 2 more answers

An object is dropped from a 15 m ledge. How fast it is moving just before it hits the ground?

Sergeeva-Olga [200]

By v^2 = u^2 + 2gh
v^2 = 0 + 2 x 9.8 x 15
v = √294
v = 17.15 m/s

4 0

2 years ago

Read 2 more answers

A solid steel bar of circular cross section has diameter d 5 2.5 in., L 5 60 in., and shear modulus of elasticity G 5 11.5 3 106

8090 [49]

Answer:

A) θ = 4.9 x 10^(-3) rad

B) τ_max = 1.173 ksi

C) τ_a = 4.786 ksi

Explanation:

We are given;

diameter; d = 2.5 inches = 0.2083 ft

Length; L = 60 inches = 5 ft

Torque; T = 300 lb.ft

Shear modulus; G = 11.5 x 10^(6) psi = 11.5 x 144 x 10^(6) lb/ft² = 1.656 x 10^(9) lb/ft²

A) Now, formula to determine angle of twist is given as;

T/I_p = Gθ/L

Where I_p is polar moment of inertia

θ is angle of twist.

Now I_p = πd⁴/32 = π(0.2083)⁴/32 = 1.85 x 10^(-4) ft⁴

Thus, making θ the subject, we have;

TL/GI_p = θ

θ = (300 x 5)/(1.656 x 10^(9) x 1.85 x 10^(-4))

θ = 4.9 x 10^(-3) rad

B) Maximum shear stress is given by the formula ;

τ_max = (Gθ/L)(d/2)

From earlier, (Gθ/L) = T/I_p

Thus, (Gθ/L) = 300/1.85 x 10^(-4) = 1621621.6216

Thus,

τ_max = 1621621.6216 x (0.2083/2)

τ_max = 168891.89 lbf/ft²

Converting to ksi = 168891.89/144000 ksi = 1.173 ksi

C) Shear stress at radial distance is given as;

τ_a = (Gθ/L)•r_a

r_a is given as 5.1 inches = 0.425m

τ_a = 1621621.6216 x 0.425 = 689189.189 lbf/ft²

Converting to ksi = 689189.189/144000 ksi = 4.786 ksi

7 0

2 years ago