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wlad13 [49]
2 years ago
9

You throw a ball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done

by gravity while it goes down.
a. Work is + on the way up and + on the way down
b. Work is + on the way up and - on the way down
c. Work is - on the way up and + on the way down
d. Work is - on the way up and - on the way down
Physics
1 answer:
Elden [556K]2 years ago
8 0

Answer:

c. Work is - on the way up and + on the way down

Explanation:

Work done is given as the product of the applied force and the displacement of the object.

Work done = F x d

Work done = mg x d

where;

g is acceleration due to gravity = 9.8 m/s²

When the ball goes up, it moves against the force of gravity which tends to pull every object downwards. Since the ball moves against gravity, the work done is negative.

Also, when the ball goes down, it moves in the direction of gravity which acts downwards. Since the ball moves in the same direction as gravity, the work done is positive.

The correct option is "C. Work is negative (-) on the way up and positive (+) on the way down"

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A 0.01-kg object is initially sliding at 9.0 m/s. It goes up a ramp (increasing its elevation by 1.5 m), and then moves horizont
barxatty [35]

Answer:

During this motion, 0.133 J of heat energy was created

Explanation:

Hi there!

Let´s calculate the energy of the object in each phase of the motion.

At first, the object has only kinetic energy (KE):

KE = 1/2 · m · v²

Where:

m = mass of the object.

v = velocity.

KE = 1/2 · 0.01 kg · (9 m/s)²

KE = 0.405 J

When the object goes up the ramp, it gains some gravitational potential energy (PE). Due to the conservation of energy, the object must convert some of its kinetic energy to obtain potential energy. By calculating the potential energy that the object acquires, we can know the loss of kinetic energy:

PE = m · g · h

Where:

m = mass of the object.

g = acceleration due to gravity (9.81 m/s²)

h = height.

PE = 0.01 kg · 9.81 m/s² · 1.5 m

PE = 0.147 J

The object "gives up" 0.147 J of kinetic energy to be converted into potential energy.

Then, after going up the ramp, the kinetic energy of the object will be:

0.405 J - 0.147 J = 0.258 J

When the object reaches the spring, kinetic energy is used to compress the spring and the object obtains elastic potential energy (EPE). Let´s calculate the EPE obtained by the object:

EPE = 1/2 · k · x²

Where:

k = spring constant.

x = compression of the spring

EPE = 1/2 · 100 N/m · (0.05 m)² = 0.125 J

Then, only 0.125 J of kinetic energy was converted into elastic potential energy. The object is at rest at the end of the motion, i.e., the object does not have kinetic energy when it compresses the spring by 5.0 cm. Since energy can´t be lost, the rest of the kinetic energy, that was not used to compress the spring, had to be converted into heat energy:

Heat energy = initial kinetic energy - obtained elastic potential energy

Heat energy = 0.258 J - 0.125 J = 0.133 J

During this motion, 0.133 J of heat energy was created.

7 0
3 years ago
A 1.5 kg orange falls from a tree and hits the ground in 0.75s. What is the speed of the orange just before it hits the ground?
Olenka [21]

The final speed of the orange is 7.35 m/s

Explanation:

The motion of the orange is a free fall motion, since there is only the force of gravity acting on it. Therefore, it is a uniformly accelerated motion with constant acceleration g=9.8 m/s^2 towards the ground. So we can use the following suvat equation:

v=u+at

where

v is the  final velocity

u is the initial velocity

a is the acceleration

t is the time elapsed

For the orange in this problem, we have

u = 0 (it is dropped from rest)

a=g=9.8 m/s^2 is the acceleration

Substituting t = 0.75 s, we find the final velocity (and speed) of the orange:

v=0+(9.8)(0.75)=7.35 m/s

Learn more about free fall:

brainly.com/question/1748290

brainly.com/question/11042118

brainly.com/question/2455974

brainly.com/question/2607086

#LearnwithBrainly

8 0
2 years ago
Oxygen is needed by all cells of most organisms for the release of
pashok25 [27]

Answer:

From the SUN

Explanation:

Hope it helps!!!

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7 0
1 year ago
Suppose your hair grows at the rate 1/31 in. per day. find the rate at which it grows in nanometers per second. because the dist
kati45 [8]
Hair grows at rate of 9.20nm/s.
7 0
3 years ago
What scenario would most likely lead to a higher level of physical fitness among people who live in a city?
ExtremeBDS [4]
More people walk to school or work hope this helps
7 0
2 years ago
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