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2 years ago

9

A plastic bottle partially filled with water floats on water, even though the density of the plastic (1.2 g/cc) is more than tha

t of water. Why is that?

1 answer:

Semmy [17]2 years ago

5 0

Answer:

True the plastic will float because of the principle of flotation or buoyancy

Explanation:

Buoyancy explains it all!!

Buoyancy is the upward force/upthrust experienced by a body immersed totally or partially in a liquid.

According to the principle of flotation:

<em>"when a body is totally or partially immersed in liquid it experiences an upthrust which is equal to the volume of fluid displaced"</em>

The plastic will float due to the fact the average density of the total volume of the plastic and the air inside it is less than the same volume of water it is floating in

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A 85-kg astronaut is stranded from his space shuttle. He throws a 1-kg hammer away from the shuttle with a velocity of 17 m/s. H

algol [13]

Answer:

0.2 m/s

Explanation:

given,

mass of astronaut, M = 85 Kg

mass of hammer, m = 1 Kg

velocity of hammer , v =17 m/s

speed of astronaut, v' = ?

initial speed of the astronaut and the hammer be equal to zero = ?

Using conservation of momentum

(M + m) V = M v' + m v

(M + m) x 0 = 85 x v' + 1 x 17

85 v' = -17

v' = -0.2 m/s

negative sign represent the astronaut is moving in opposite direction of hammer.

Hence, the speed of the astronaut is equal to 0.2 m/s

4 0

2 years ago

A ball was dropped from a height of 10 feet. Each time it hits the ground, it bounces 4/5 of its previous height. Find the total

Shtirlitz [24]

Answer:

d = 90 ft

Explanation:

As we know that after each bounce it reaches to 4/5 times of initial height

so we can say

$h_2 = \frac{4}{5}h$

so the distance covered is given as

$d = h + 2(\frac{4}{5}h) + 2(\frac{4}{5})^2h + 2(\frac{4}{5})^3h........$

here we know that

h = 10 feet

$d = h + 2(\frac{4}{5}h)(1 + \frac{4}{5} + (\frac{4}{5})^2 + ...........)$

$d = 10 + 2(\frac{4}{5}(10))(\frac{1}{1 - \frac{4}{5}})$

$d = 90 ft$

8 0

2 years ago

What does an element’s molar mass tell you about the element?

olga nikolaevna [1]

Answer:

The molar mass of a compound tells you the mass of one mole of that substance. In other words, it tells you the number of grams per mole of a compound.

7 0

1 year ago

You have a pulley 10.4 cm in diameter and with a mass of 2.3 kg. You get to wondering whether the pulley is uniform. That is, is

madreJ [45]

Answer:

Explanation:

Given

Diameter of Pulley=10.4 cm

mass of Pulley(m)=2.3 kg

mass of book $(m_0)=1.7 kg$

height(h)=1 m

time taken=0.64 s

$h=ut+frac{at^2}{2}$

$1=0+\frac{a(0.64)^2}{2}$

$a=4.88 m/s^2and [tex]a=\alpha r$

where $\alpha$ is angular acceleration of pulley

$4.88=\alpha \times 5.2\times 10^{-2}$

$\alpha =93.84 rad/s^2$

And Tension in Rope

$T=m(g-a)$

$T=1.7\times (9.8-4.88)$

T=8.364 N

and Tension will provide Torque

$T\times r=I\cdot \alpha$

$8.364\times 5.2\times 10^{-2}=I\times 93.84$

$I=0.463\times 10^{-2} kg-m^2$

$I_{original}=\frac{mr^2}{2}=0.31\times 10^{-2}kg-m^2$

Thus mass is uniformly distributed or some more towards periphery of Pulley

4 0

2 years ago

A ball starts at rest and rolls down an inclined plane. The ball reaches 7.5 m/s in 3 seconds. What is the acceleration?

just olya [345]

Answer:

$a=2.5\ m/s^2$

Explanation:

<u>Motion With Constant Acceleration </u>

It's a type of motion in which the velocity of an object changes uniformly over time.

The equation that describes the change of velocities is:

$v_f=v_o+at$

Where:

a = acceleration

vo = initial speed

vf = final speed

t = time

Solving the equation for a:

$\displaystyle a=\frac{v_f-v_o}{t}$

The ball starts at rest (vo=0) and rolls down an inclined plane that makes it reach a speed of vf=7.5 m/s in t=3 seconds.

The acceleration is:

$\displaystyle a=\frac{7.5-0}{3}$

$\boxed{a=2.5\ m/s^2}$

7 0

2 years ago