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3 years ago

WILL GIVE BRAINLIEST! If a system stores kinetic energy, which choice must be true?

2 answers:

7 0

The last choice is correct, in order to have kinetic energy a object must be in motion, if not then the object has no kinetic energy

Grace [21]3 years ago

4 0

The molecules and subatomic particles must be moving.

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Paul’s 10 kg baby sister Susan sits on a mat. Paul pulls the mat across the floor using a rope that is angled 30° above the floo

kiruha [24]

Answer:

The speed of Susan is 2.37 m/s

Explanation:

To visualize better this problem, we need to draw a free body diagram.

the work is defined as:

$W=F*d*cos(\theta)$

here we have the work done by Paul and the friction force, so:

$W_p=F_p*d*cos(0)\\F_p=30N*cos(30^o)=26N\\W_p=26*3*(1)=78J$

$W_f=F_f*d*cos(180)\\F_f=\µ*(10*9.8-30N*sin(30^o))=16.6N\\W_p=16.6*3*(-1)=50J$

Now the change of energy is:

$W_p-W_f=\frac{1}{2}m*v^2\\v=\sqrt{\frac{2(78J-50J)}{10kg}}\\v=2.37m/s$

4 0

3 years ago

Read 2 more answers

How could you use a rock to measure the height of your ceiling?

Annette [7]

Answer:

I mean this is what I think

Explanation:

you would need to place a rock on top of each other until you reach the ceiling

It seems logical to me

7 0

3 years ago

Which of the following statements about the conservation of momentum is not correct? Momentum is conserved for a system of objec

Olin [163]

Answer:

wrong statement : Momentum is not conserved for a system of objects in a head-on collision.

Explanation:

In a head on collision of two objects , two equal and opposite forces are created at the point of collision . These two forces create two impulses in opposite direction which results in equal and opposite changes in momentum in each of them . Hence net change in momentum is zero. In this way momentum is conserved in head on collision of two objects.

3 0

4 years ago

A car takes off from rest takes of from rest and covers a distance of 80m on a straight road in 10s.Calculate the magnitude of i

hodyreva [135]

Initial velocity (u) = 0 m/s [the car was at rest]
Distance (s) = 80 m
Time (t) = 10 s
Let the magnitude of acceleration be a.
By using the equation of motion, $s = ut + \frac{1}{2} a {t}^{2}$ we get, $80 = 0 \times 10 + \frac{1}{2} \times a \times {10}^{2} \\ = > 80 = \frac{1}{2} \times 100a \\ = > 80 = 50a \\ = > a = \frac{80}{50} \\ = > a = 1.6$

Answer:

The magnitude of its acceleration is 1.6 m/s^2.

Hope you could get an idea from here.

Doubt clarification - use comment section.

4 0

3 years ago

_____ has a longer wavelength than _____. _____ has a longer wavelength than _____. Blue ... green Green ... yellow Red ... gree

nadya68 [22]

Answer:

red has a longer wavelength than yellow. Yellow has a longer wavelength than green.

Explanation

in the visible spectrum a color with high frequency contains shorter wavelength.In this case red color has high wavelength followed by yellow followed by green,blue and violet.

3 0

3 years ago

Read 2 more answers