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3 years ago

Which of the following describes density only in terms of metric units?

1 answer:

7 0

A) Kilograms per cubic meter. Every other option either contains pounds or feet, which are both units of measurement from the standard system, not the metric system.

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A child of mass 40.0 kg is in a roller coaster car that travels in a loop of radius 7.00 m. at point a the speed of the car is 1

pav-90 [236]

I attached the missing picture.
The force of seat acting on the child is a reaction the force of child pressing down on the seat. This is the third Newton's law. The force of a child pressing down the seat and the force of the seat pushing up on the child are the same.
There two forces acting on the child. The first one is the gravitational force and the second one is centrifugal force. In this example, the force of gravity is always pulling down, but centrifugal force always acts away from the center of circular motion.
Part A
For point A we have:
$F_a=F_cf-F_g$
In this case, the forces are aligned, centrifugal is pointing up and gravitational is pulling down.
$F_a=m\frac{v^2}{r}-mg=179 $N$
Part B
At the point, B situation is a bit more complicated. In this case force of gravity and centrifugal force are not aligned. We have to look at y components of this forces, y-axis, in this case, is just pointing upward.
$F=F_{cf}\cos(30)-mg=m\frac{v^2}{r}\cos(30)-mg=153.2$N$
Part C
The child will stay in place at point A when centrifugal force and force of gravity are in balance:
$F_g=F_{cf}\\
mg=m\frac{v^2}{r}\\
gr=v^2\\
v=\sqrt{gr}=8.29\frac{m}{s}$

6 0

3 years ago

In the lesson a thermos is presented as an example of an isolated energy system. How could you change the thermos into an open e

iVinArrow [24]

If you want to change the thermos into an open energy system, you have to remove the lid. Once the lid is removed, the energy is no longer contained inside the thermos bottle. From the bottle, the energy dissipates to the environment.

7 0

3 years ago

Read 2 more answers

If the box is a distance 1.81 m from the rear of the truck when the truck starts, how much time elapses before the box falls off

alexira [117]

If the box is a distance 1.81 m from the rear of the truck when the truck starts, ... Force of Friction = mu_s * Normal Force( M * G) ... The box starts moving! ... Now that the box is moving, the bed of the truck pulls at it with 17.4 ... out how long it will take the box to reach the back of the truck. ... T^2 = 2 * 1.81 / .64

4 0

4 years ago

A virtual image is formed 17.0 cm from a concave mirror having a radius of curvature of 39.0 cm. (a) Find the position of the ob

Wittaler [7]

Explanation:

Image distance, v = -17 cm (-ve for virtual image)

Radius of curvature of concave mirror, R = 39 cm

Focal length, f = -19.5 cm (-ve for a concave mirror)

(a) Using mirror's formula as :

$\dfrac{1}{v}+\dfrac{1}{u}=\dfrac{1}{f}$

$\dfrac{1}{u}=\dfrac{1}{f}-\dfrac{1}{v}$

$\dfrac{1}{u}=\dfrac{1}{-19.5}-\dfrac{1}{(-17)}$

u = 132.6 cm

So, the object is placed 132.6 cm in front of the mirror.

(b) Magnification of the mirror, $m=\dfrac{-v}{u}$

$m=\dfrac{-17}{132.6}$

m = -0.128

Hence, this is the required solution.

7 0

3 years ago

An empty rubber balloon has a mass of 12.5 g. The balloon is filled with helium at a density of 0.181 kg/m3. At this density the

Taya2010 [7]

Answer:

5.5 N

Explanation:

mass of balloon (m) = 12.5 g = 0.0125 kg

density of helium = 0.181 kg/m^{3}

radius of the baloon (r) = 0.498 m

density of air = 1.29 kg/m^{3}

acceleration due to gravity (g) = 1.29 m/s^{2}

find the tension in the line

the tension in the line is the sum of all forces acting on the line

Tension =buoyant force + force by helium + force of weight of rubber

force = mass x acceleration

from density = \frac{mass}{volume} , mass = density x volume

buoyant force = density x volume x acceleration

where density is the density of air for the buoyant force

buoyant force = 1.29 x (\frac{4]{3} x π x 0.498^{3}) x 9.8 = 6.54 N

force by helium = density x volume x acceleration

force by helium = 0.181 x (\frac{4]{3} x π x 0.498^{3}) x 9.8 = 0.917 N

force of its weight = mass of rubber x acceleration

force of its weight = 0.0125 x 9.8 = 0.1225 N

Tension = buoyant force + force by helium + force of weight of rubber

the force of weight of rubber and of helium act downwards, so they

carry a negative sign.

Tension = 6.54 - 0.917 - 0.1225 = 5.5 N

8 0

3 years ago