Represent the following sentence as an algebraic expression, where "a number" is the

4. Lead has a density of 11.5g/cmº. A rectangular block of lead measures 7cm x5cmx2cm.

lisov135 [29]

Answer:

(a) 70cm³

(b) 805 grams

Explanation:

(a) V = L×B×H

= 7cm×5cm×2cm

= 35cm×2cm

= 70cm³

(b) Mass = Volume × Density

= 70cm³ × 11.5g/cm³

= 805 grams

3 0

3 years ago

A girl coasts down a hill on a sled, reaching level ground at the bottom with a speed of 7.4 m/s. The coefficient of kinetic fri

Amanda [17]

Answer: 62.22 meters

Explanation:

Two solve this, we need to know first how the Sled interact with the snow. While the Sled runs over the snow, the snow opposes to it movement, this is call friction. Frictions creates is a force that goes against any movement and is caused by the interaction between surfaces.

Friction can be calculated using the following equation:

Friction's Force (Ff) = m*N

Where m is the Frictions coficient and N is call Normal, which is a force created by the contact between any weight and a surface. Because the sled is and the surface are totally horizontal, the Normal is equal to the Sled's Weight.

So for this case, we can calculate the Friction's Force:

Ff = 0.045 * 735 N

Ff = 33,07 N

This force will cause a negative acceleration the Sled causing it to slow down and finally stop. To know this accelaration we can use the following equation:

Force (F) = Mass (m) * Accelaration (a)

Looking for the accelaration:

Acceleration (a) = F / M

As a side note:

Mass (M) = F / a (1)

Where we know that F is equal to our Friction Force (Ff) and the Mass for the girl and the Sled can be obtained using the previous equation (1) like this

Girl and sled Mass (M) = 735 N / (9.81 m/s)

M = 74,92 Kg

This is posible, because the Girl and The Sled are aplying a Force on the ground equal to 735 N. The accelartion for their mass is the gravity

Now, with the mass we can found the Accelaration caused by friction:

Acceleration (a) = Ff / M

Accelaration (a) = 33,07 N / 74,92 Kg

a = 0,44 $m/s^{2}$

To know how far the Sled travel we can use the following equation:

$V_{f} ^{2} = V_{0} ^{2} + 2ax$

Where Vf is the Final Velocity, which is when the sled finally stops (Vf = 0), Vo is the Initial Speed of the Sled equal to 7.4 m/s and a is equal to the negative accelaration that causes the friction.

$(0)^{2} = (7.4 m/s)^{2} + 2(-0,44)x$

Searching for x:

$x = \frac{0 - (7.4 m/s)^{2} }{-0.88}$

$x = 62.22 meters$

The girls will run over the snow 62.22 meter until finally stopping

4 0

3 years ago

How many moles of oxygen atoms are in 2 moles of water?

harkovskaia [24]

2 water molecules contain 4 hydrogen atoms and 2 oxygen atoms. a mile of water molecules contains 2 moles of hydrogen atoms and 1 mole of oxygen atoms !

hope this helped :)

6 0

3 years ago

An archer shot a 0.06 kg arrow at a target. The arrow accelerated at 5,000 m/s2 to reach a speed of 50.0 m/s as it left the bow.

laila [671]

Answer:

300 N

Explanation:

The net force acting on the arrow is given by Newton's Second Law:

$F=ma$