Can somebody help me come up with a speech about gravity

t's Peggy Sue's birthday and she's about to blow out the candles on her cake. Brother Roger stops the party when he shouts: "Loo

Ket [755]

Answer:

D) Roger is incorrect. Only a chemical change is taking place as evidenced by the light and heat of the burning candles.

Explanation:

- A physical change is a change in which there is no formation of new substances. Examples of physical changes are the melting or the evaporation of a substance (all phase transitions are examples of physical changes): in such cases, there is no formation of new substances.

- A chemical change is a change in which new substances form. Examples of chemical changes are the chemical reactions: for instance, when a candle burns, a reaction is taken place (oxygen is burnt, transforming into carbon dioxide + heat + light, so this is an example of chemical change).

Therefore, the correct answer is

D) Roger is incorrect. Only a chemical change is taking place as evidenced by the light and heat of the burning candles.

5 0

3 years ago

Read 2 more answers

What has more gravity-Earth's moon or the Sun?Why?

charle [14.2K]

Answer:

Even though the sun is much more massive and therefore has stronger overall gravity than the moon, the moon is closer to the earth so that its gravitational gradient is stronger than that of the sun.

Explanation:

7 0

3 years ago

How much dirt is there in a hole 3 feet deep, 6 ft long and 4 ft wide?

katrin [286]

V = l x w x h
v = 3 x 6 x 4
v = 72

5 0

3 years ago

A 30.0-g object connected to a spring with a force constant of 40.0 N/m oscillates with an amplitude of 6.00 cm on a frictionles

Naddika [18.5K]

Answer:

a) 72mJ

b) 0.33m/s

c) 54mJ

d) 18mJ

Explanation:

(a) The total energy of the system is given by:

$E_T=\frac{1}{2}kA^2$

where k is the force constant and A is the amplitude. By replacing we get:

$E_T=\frac{1}{2}(40N/m)(0.06m)^2=0.072J$ = 72mJ

(b) we can get the speed by the conservation of energy (the kinetic energy and potential energy must equal the total energy in any place):

$E_T=E_k+E_p\\\\\frac{1}{2}kA^2=\frac{1}{2}mv^2+\frac{1}{2}kx^2\\\\v=\sqrt{\frac{kA^2-kx^2}{m}}=\sqrt{\frac{(40N/m)((0.06m)^2-(0.0115m)^2)}{0.03kg}}=0.33m/s$

where we have used that x=1.15cm=0.0115m; A=6.00cm=0.06m

(c) Again, by the conservation of energy:

$E_k=\frac{1}{2}k(A^2-x^2)=\frac{1}{2}(40N/m)((0.06m)^2-(0.03m)^2)=0.054J=54mJ$

(d) $E_p=\frac{1}{2}kx^2=\frac{1}{2}(40.0N/m)(0.03m)^2=0.018J=18mJ$

hope this helps!!

6 0

3 years ago

Bored, a boy shoots his pellet gun at a piece of cheese that sits, keeping cool for dinner guests, on a massive block of ice. On

lukranit [14]

Answer

mass of pellet (m₁) =1.3 g

mass of the system when pellet sticks to the cheese is (m₂)

m₂ = 109 + 1.3 = 110.3 g

velocity of the muzzle = 73 m/s

now using conservation of momentum

m₁ v₁ =m₂v₂

where v₁ is velocity of the pellet and v₂ is the initial velocity of the (pellet+cheese ) system

m₁ v₁ =m₂v₂

1.3 x 73 = 110.3 x v₂

v₂ = 0.86 m/s

initial velocity of (pellet+cheese)system = v₁

and final velocity = 0

using

v₁² - 0 = 2 a s

where a is the deceleration and s =25 cm

0.86² - 0 = 2 a s

0.86² - 0 = 2 x a x 0.25

a = 1.48 m/s²

now, calculation of force of friction

m₂ a = μ m₂ g

$\mu=\dfrac{a}{g}$

where μ is the coefficient of friction

$\mu=\dfrac{0.86}{9.8}$

μ = 0.087

4 0

4 years ago