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3 years ago

Straw polls are___. A. scientifically based B. representative samples C. biased sampling D. cluster samples

1 answer:

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Straw polls are considered to be a form of biased sampling. An example of a straw poll is an unofficial vote like who you would like to be the President without actually casting your ballot.

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a 1600 kg car on flat ground is moving 6.25 m/s. its engine creates 1150 N forward force as the car moves 45.8 m. what is it fin

Sveta_85 [38]

Answer:

83,900 J

Explanation:

First, find the acceleration:

F = ma

1150 N = (1600 kg) a

a = 0.719 m/s²

Now find the final velocity.

Given:

Δx = 45.8 m

v₀ = 6.25 m/s

a = 0.719 m/s²

Find: v

v² = v₀² + 2aΔx

v² = (6.25 m/s)² + 2 (0.719 m/s²) (45.8 m)

v = 10.2 m/s

Now find the final KE:

KE = ½ mv²

KE = ½ (1600 kg) (10.2 m/s)²

KE = 83,920 J

Rounded to three significant figures, the final kinetic energy is 83,900 J.

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4 years ago

The tip of the second hand of a clock moves in a circle of 20 cm circumference. In one minute the hand makes a complete revoluti

Cerrena [4.2K]

Answer:

$v_{avg} = 0$

Explanation:

As we know that average velocity is defined as the ratio of total displacement of the object and its time interval.

so here we can say

$v_{avg} = \frac{displacement}{time}$

now we know that in one complete revolution the total displacement of the tip of the seconds hand is zero

because it will have same position after one complete revolution from where it starts

so here we can say that the average velocity will be zero

$v_{avg} = 0$

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3 years ago

The linear momentum of a truck of mass 5000 kg that is moving at a velocity of +30 m/a is ___ kg m/s

miv72 [106K]

Linear momentum of a truck is 1,50,000 kg.m/s

Explanation:

Linear momentum is the product of the mass and velocity of an object. It is a vector quantity, which have a magnitude and a direction.

Linear momentum is a property of an object which is in motion with respect to a reference point (i.e. any object changing its position with respect to the reference point).

It's SI units are kg.m/s

Linear momentum is a vector quantity.

Linear momentum formula (p) = mass × velocity

Given data mass = 5000 kg ; velocity = 30 m/s

P = 5000 × 30

Linear momentum p= 1,50,000 kg.m/s

7 0

3 years ago

A hot cube of iron was heated up using 1500 J of thermal energy and was placed in a beaker of water. Before it was heated, the i

Mariana [72]

Answer:

451.13 J/kg.°C

Explanation:

Applying,

Q = cm(t₂-t₁)............... Equation 1

Where Q = Heat, c = specific heat capacity of iron, m = mass of iron, t₂= Final temperature, t₁ = initial temperature.

Make c the subject of the equation

c = Q/m(t₂-t₁).............. Equation 2

From the question,

Given: Q = 1500 J, m = 133 g = 0.113 kg, t₁ = 20 °C, t₂ = 45 °C

Substitute these values into equation 2

c = 1500/[0.133(45-20)]

c = 1500/(0.133×25)

c = 1500/3.325

c = 451.13 J/kg.°C

4 0

3 years ago

At the local swimming hole, a favorite trick is to run horizontally off a cliff that is 8.0 m above the water. One diver runs of

Alika [10]

Answer:

Number of revolutions=1.532 revolutions

Explanation:

Given data

Distance s=8.0 m

Angular speed a=1.2 rev/s

To find

Number of revolutions

Solution

From the equation of simple motion we not that

$S=ut+1/2gt^{2}\\ where\\u=0\\So\\8.0m=0+(1/2)(9.8m/s^{2} )t^{2}\\ t^{2}=\frac{8.0m}{0.5*9.8m/s^{2} } \\ t^{2}=1.63\\t=\sqrt{1.63} \\t=1.28s$

So for the number of revolutions she makes is given as

$n=a*t\\n=(1.2rev/s)(1.28s)\\n=1.532revolutions$

8 0

3 years ago