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dolphi86 [110]
3 years ago
7

A book starts on a shelf 1 m off of the ground. You then move the book to a higher shelf that is 3 m off of the ground. If the s

ystem gained 20 J of gravitational potential energy, what is the mass of the book?
Physics
1 answer:
JulsSmile [24]3 years ago
4 0

Answer:

Using g = 9.8: 1.02 kg, Using g = 10: 1 kg

Explanation:

E = mgh

20 = m(9.8)(3 - 1)

20 = 9.8m(2)

20 = 19.6m

m = 1.02 kg

I'm now assuming you may be using a g constant of 10, thus the close integer result, in which case the mass would be exactly 1 kilogram.

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A block whose weight is 45 N rests on a horizontal table. A horizontal force of 36 N is applied to the block. The coefficient of
riadik2000 [5.3K]

Answer:

1.5 m/s²

Explanation:

For the block to move, it must first overcome the static friction.

Fs = N μs

Fs = (45 N) (0.42)

Fs = 18.9 N

This is less than the 36 N applied, so the block will move.  Since the block is moving, kinetic friction takes over.  To find the block's acceleration, use Newton's second law:

∑F = ma

F − N μk = ma

36 N − (45 N) (0.65) = (45 N / 9.8 m/s²) a

6.75 N = 4.59 kg a

a = 1.47 m/s²

Rounded to two significant figures, the block's acceleration is 1.5 m/s².

Usually the coefficient of static friction is greater than the coefficient of kinetic friction.  You might want to double check the problem statement, just to be sure.

6 0
3 years ago
Do it in order. <br> from smallest to largest
Sholpan [36]

Answer:

The earth, The sun, the solar system and the milky way.

7 0
2 years ago
An ant can travel approximately 30 meters per minute. How many meters could an ant move in 45 minutes.
Nastasia [14]

Answer:

From what I see, it's saying that every minute, the ant can move 30 meters.  So how many meter would it move in 45 minutes?

30 meters = 1 min

x meters = 45 min

1 min x 45 = 45 min

30 meters x 45 = 1,350 meters

So, I believe the answer would be 1,350 meters.

hope this helps. :>

8 0
3 years ago
A 0.45kg baseball is pitched towards home plate at 20 m/s. The ball is hit back towards the pitcher with a speed of 30 m/s. What
Inessa05 [86]

Answer:

4.5kgm/s

Explanation:

Change in momentum is expressed as

Change in momentum = m(v-u)

M is the mass

V is the final velocity

u is the initial velocity

Given

m=0.45kg

v = 30m/s

u = 20m/s

Substitute

Change in momentum = 0.45(30-20)

Change in momentum = 0.45×10

Change in momentum = 4.5kgm/s

3 0
3 years ago
Which of the following statements explains why a race car going around a curve is accelerating, even if the speed is constant? A
Tom [10]

OPTION C The car is accelerating because the direction of velocity is changing explains why a race car going around a curve is accelerating, even if the speed is constant

  • When a body is in uniform circular motion ( constant speed ), it will continuously cheanges its direction and so the body is accelerating
  • The rate at which an item changes its velocity is known as acceleration, a vector variable. If an object's velocity is changing, it is accelerating.
  • As a vector quantity, acceleration has a direction attached to it. The acceleration vector's direction is determined by two factors: if the thing is slowing down or speeding up the direction the thing is travelling in (+ or -)

  • The following general rule is used to calculate acceleration:

An object's acceleration will be in the opposite direction of its velocity if it is slowing down.

You may use this basic concept to determine if an object's acceleration is positive or negative, to the right or left, up or down, etc.

To know more about  acceleration visit : brainly.com/question/12550364

#SPJ4

7 0
1 year ago
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