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3 years ago

Which is greater, the mass of the compounds before a chemical reaction or the mass of the compounds after a chemical reaction?

Physics

1 answer:

harkovskaia [24]3 years ago

7 0

The masses before and after are equal

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During the last shot of the game, the basketball goes from rest to 15 m/s and reaches the backboard in 0.41 s. What was the acce

Anna [14]

Answer: a= 37m

Explanation: V= 15 m/s (Velocity) t= 0.41s (time) formula: a= v/t

15 m/s / 0.41 (15 divided by 0.41) = 36.583m

There are 2 significant digits, 36, you look at the third digit, either round up or down in this case up to 36. a= 37m

5 0

3 years ago

Which of the follow represent a chemical changes

mixer [17]

Answer:

C) steel turning to rust in salt air

Explanation:

The missing options are:

A) ice melting to form liquid water

B) water boiling to form steam

C) steel turning to rust in salt air

D) sugar dissolving into hot coffee

In a chemical change the atoms of the reacting compounds are reordered forming new compounds. In a chemical change, new compounds appear, but in a physical change not.

Then, change of states like ice melting and water boiling are not chemical changes.

During steel rust, components of steel, like iron, are oxidized, that is, reacts with oxygen forming oxides.

The dissolution of sugar into hot coffee is a physical change in which sugar molecules get further apart in the coffee, but they don't change.

5 0

4 years ago

When must scientific theories be changed

madreJ [45]

Answer:

when new information disproving the current theory becomes available.

Explanation:

hope this helps..

4 0

2 years ago

A ball is thrown vertically upwards with an initial velocity of 20.00 m/s. Neglecting air resistance, how long is the ball in th

algol [13]

Answer:

1) The greatest height attained by the ball equals 20.387 meters.

2) The time it takes for the ball to reach 15 meters approximately equals 1 second.

Explanation:

The greatest height will be attained when the ball stop's in the air and starts falling back to the earth.

thus using third equation of kinematics we obtain the height attained as

$v^2=u^2+2as$

where

'v' is the final speed of the ball

'u' is the initial speed of the ball

'a' is the acceleration that the ball is under which in this case equals 9.81 $m/s^{2}$

's' is the distance it covers

Thus for maximum height applying the values in the equation we get

$0=20^{2}-2\times 9.81\times h\\\\\therefore h=\frac{20^{2}}{2\times 9.81}=20.387meters$

Using the same equation we can find the speed of the ball when it reaches 15 meters of height as

$v^2=20^{2}-2\times 9.81\times 15\\\\v^{2}=105.7\\\\\therefore v=10.28m/s$

the time it takes to reduce the velocity to this value can be found by first equation of kinematics as

$v=u+at\\\\t=\frac{v-u}{a}\\\\t=\frac{10.28-20}{-9.81}=0.991seconds\approx 1second$

4 0

4 years ago

The standard measure used to compare sound intensities is the ______ .

uranmaximum [27]

The answer is Decibels. <span />

4 0

3 years ago

Read 2 more answers