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4 years ago

8

A mover pushes a 30.0 kg crate across a wooden floor at a constant speed of 0.75 m/s. If the coefficient of static friction for

wood-on-wood is 0.20, what is the normal force exerted by the floor on the crate?

1 answer:

liraira [26]4 years ago

3 0

Answer:

294.3 N

Explanation:

In this situation, we are told that the crate is not accelerating in the horizontal plane. But also it is not accelerating in the vertical plane. Meaning that the sum of all vertical forces add up to zero.

Fnet = ma

Weight + Normal force = mass * acceleration

-(30 kg * 9.81 m/s²) + Normal force = 30.0 kg * 0 m/s²

Normal force = 294.3 N

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Estimate (a) the maximum, and (b) the minimum thermal conductivity values (in W/m-K) for a cermet that contains 83 vol% carbide

velikii [3]

Answer:

k_max = 31.82 w/mk

k_min = 17.70 w/mk

Explanation:

a) the maximum thermal conductivity is given as

$k_{max} = k_m*v_m + k_p*v_p$

where k_m is thermal conductvitiy of metal

k_p is thermal conductvitiy of carbide

v_m = proportion of metal in the cement = 0.17

v_p = proportion of carbide in the cement = 0.83

= 66*0.17 + 28*0.83

k_max = 31.82 w/mk

b) the minimum thermal conductivity is given as

$k_{min} = \frac{k_{carbide}* k_{metal}}{k_{metal} v_{carbide} +k_{metal} v_{carbide}}$

= \frac{28+66}{28*0.17 +66*0.83}

k_min = 17.70 w/mk

7 0

3 years ago

Six automobiles are initially traveling at the indicated velocities. The automobiles have different masses and velocities. The d

Mumz [18]

Answer:

Part a)

Purple car = Light Blue car > (Red car = Yellow Car = Blue car) > Green Car

Part b)

Purple car = Light Blue car > (Red car = Yellow Car = Blue car) > Green Car

Part c)

Purple car = Light Blue car > (Red car = Yellow Car = Blue car) > Green Car

Explanation:

Red car

mass = 1000 kg

speed = 10 m/s

Yellow car

mass = 2000 kg

speed = 5 m/s

Blue car

mass = 500 kg

speed = 20 m/s

Light Blue car

mass = 1000 kg

speed = 20 m/s

Green car

mass = 500 kg

speed = 10 m/s

Purple car

mass = 4000 kg

speed = 5 m/s

Part a)

Now we know that momentum of each car is product of mass and velocity

so we will have

Red Car

$P_1 = m v$

$P_1 = (1000)(10)$

$P_1 = 10^4 kg m/s$

Yellow Car

$P_2 = m v$

$P_2 = (2000)(5)$

$P_2 = 10^4 kg m/s$

Blue Car

$P_3 = m v$

$P_3 = (500)(20)$

$P_3 = 10^4 kg m/s$

Light Blue Car

$P_4 = m v$

$P_4 = (1000)(20)$

$P_4 = 2\times 10^4 kg m/s$

Green Car

$P_5 = m v$

$P_5 = (500)(10)$

$P_5 = 5 \times 10^3 kg m/s$

Purple Car

$P_6 = m v$

$P_6 = (4000)(5)$

$P_6 = 2\times 10^4 kg m/s$

So the momentum is given as

Purple car = Light Blue car > (Red car = Yellow Car = Blue car) > Green Car

Part b)

Impulse is given as change in momentum so here we can say that final momentum of all the cars will be zero as they all stops and hence the impulse is same as initial momentum of the car

so the order of impulse from largest to least is given as

Purple car = Light Blue car > (Red car = Yellow Car = Blue car) > Green Car

Part c)

Force is defined as rate of change in momentum

Now let say all cars will stop in same time interval

so we will have

$Force = \frac{impulse}{time}$

so we will have

force is in same order as that of impulse

so it is given as

Purple car = Light Blue car > (Red car = Yellow Car = Blue car) > Green Car

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4 years ago

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eimsori [14]

Answer:

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3 years ago

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A 120 V potential difference is applied to a space heater that dissipates 674 W during operation. (a) What is its resistance dur

Annette [7]

Answer:

(a) 21.36 ohms

(b) 5.62 A

Explanation:

Parameters given:

Potential difference, V = 120 V

Power, P = 674 W

(a) Power is given as:

P = V²/R

Where R is resistance

=> R = V²/P

R = 120²/674

R = 14400/674

R = 21.36 ohms

(b) Power is also given as:

P = I*V

Where I = Current (time rate of flow of Electric charge)

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xenn [34]

Answer:

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Explanation:

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