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3 years ago

Rusting metal is an example of a _________ change. A) phase B) state C) chemical D) physical

Physics

2 answers:

elena55 [62]3 years ago

8 0

Answer:

chemical

Explanation:

chemical change

sergeinik [125]3 years ago

6 0

Answer:

C. Chemical Change

Explanation:

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A 6 kg bowling ball moves with a speed of 3 m/s. How fast does a 7 kg bowling ball need to move so that it has the same kinetic

maw [93]

Answer: 7 kg bowling ball must move with a speed of 2.8 m/s so that it has the same kinetic energy.

Explanation:

Kinetic energy is the energy possessed by a body by virtue of its motion.

$K.E=\frac{1}{2}mv^2$

m = mass of object

v= velocity of the object

$K.E=\frac{1}{2}\times 6kg\times (3m/s)^2=27Joules$

b) for a 7 kg bowl to have kinetic energy of 27 Joules:

$27J=\frac{1}{2}\times 7kg\times v^2$

$v^2=7.7$

$v=2.8m/s$

Thus 7 kg bowling ball must move with a speed of 2.8 m/s so that it has the same kinetic energy

4 0

3 years ago

HELP ASAP TIMED TEST

balu736 [363]

Answer:

<em>Correct choice: b 4H</em>

Explanation:

<u>Conservation of the mechanical energy</u>

The mechanical energy is the sum of the gravitational potential energy GPE (U) and the kinetic energy KE (K):

E = U + K

The GPE is calculated as:

U = mgh

And the kinetic energy is:

$\displaystyle K=\frac{1}{2}mv^2$

Where:

m = mass of the object

g = gravitational acceleration

h = height of the object

v = speed at which the object moves

When the snowball is dropped from a height H, it has zero speed and therefore zero kinetic energy, thus the mechanical energy is:

$U_1 = mgH$

When the snowball reaches the ground, the height is zero and the GPE is also zero, thus the mechanical energy is:

$\displaystyle U_2=\frac{1}{2}mv^2$

Since the energy is conserved, U1=U2

$\displaystyle mgH=\frac{1}{2}mv^2 \qquad\qquad [1]$

For the speed to be double, we need to drop the snowball from a height H', and:

$\displaystyle mgH'=\frac{1}{2}m(2v)^2$

Operating:

$\displaystyle mgH'=4\frac{1}{2}m(v)^2 \qquad\qquad [2]$

Dividing [2] by [1]

$\displaystyle \frac{mgH'}{mgH}=\frac{4\frac{1}{2}m(v)^2}{\frac{1}{2}m(v)^2}$

Simplifying:

$\displaystyle \frac{H'}{H}=4$

Thus:

H' = 4H

Correct choice: b 4H

4 0

3 years ago

Which two particles are present in the nucleus of an atom? Electrons and neutrons Electrons and molecules 1 TH O Protons and neu

aleksandrvk [35]

Answer:

Protons and neutrons

Explanation:

8 0

3 years ago

write down the total momentum for two marbles of mass,m, both moving at velocity, v. What is the kinetic energy of the system.

frosja888 [35]

Mv + mv = 2mv providing each momentum is in the same direction.
1/2 mv^2 + 1/2 mv^2 = mv^2

4 0

3 years ago

Read 2 more answers

Two vehicles, a car and a truck, leave an intersection at the same time. the car heads east at an average speed of 50 miles pe

olya-2409 [2.1K]

The car heads east at an average speed of 50 miles per hour from the intersection point towards East. The truck heads east at an average speed of 60 miles per hour from the intersection point towards South.

The distance of car from the intersection point after t hours is $50t$ .

The distance of truck from the intersection point after t hours is $60t$ .

Since these distances are perpendicular to each other, distance apart d (in miles) at the end of t hours is

$d=\sqrt{(50t)^2+(60t)^2} \\ d=10\sqrt{61} t\\ d=78.1t$

Thus the distance apart is $d=78.1t \;miles$

5 0

3 years ago