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3 years ago

I NEED HELP PLEASE, THANKS!

Physics

1 answer:

Travka [436]3 years ago

6 0

Explanation:

When a person is standing still, the forces acting on them (weight force pulling down and normal force pushing up) are equal and opposite, so the net force is balanced. So the person will continue to be at rest, unless the net force becomes unbalanced.

When a person falls with a parachute, the forces acting on them (weight force pulling down and air resistance pushing up) are equal and opposite, so the net force is balanced. So the person will continue to fall at the same speed until the net force becomes unbalanced.

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A baseball of mass 300-g is hit at a velocity of 40 m/s. If the ball is caught by the third baseman and the ball penetrates 2.0

OlgaM077 [116]

The force is -12,000 N

Explanation:

First of all, we calculate the acceleration of the ball, by using the following suvat equation:

$v^2-u^2=2as$

where:

v = 0 is the final velocity of the baseball (it comes to rest)

u = 40 m/s is the initial velocity

a is the acceleration

s = 2.0 cm = 0.02 m is the displacement of the ball

Solving for a,

$a=\frac{v^2-u^2}{2s}=\frac{0-40^2}{2(0.02)}=-40,000 m/s^2$

Now we can calculate the average force exerted on the ball, by using Newton's second law:

$F=ma$

where

m = 300 g = 0.3 kg is the mass of the ball

$a=-40,000 m/s^2$ is the acceleration

Substituting,

$F=(0.3)(-40,000)=-12,000 N$

where the negative sign indicates that the direction of the force is opposite to the direction of motion of the ball.

Learn more about forces:

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8 0

3 years ago

A 78−kg skier is sliding down a ski slope at a constant velocity. The slope makes an angle of 21° above the horizontal direction

Feliz [49]

Answer:

274N 0.41

Explanation:

As he is sliding down in a constant speed then the force that accelerates him (weight) and the force that slows his down (friction) are equal.

then

<em>friction=mass x gravity x sin(21)</em>

Fr=78kg x 9.8m/s2 x sin(21)=274N

<em>friction= coefficient of kinetic friction x normal force of from the slope</em>

Fr= u x 78kg x 9.8m/s2 x cos(21)=274N

Fr= u x 78kg x 9.8m/s2 x cos(21)=274Nu=274/677=0.41

8 0

3 years ago

According to perception of movement, in order to sense movement, humans need to see an object _____.

lesya692 [45]

Answer: The correct answer for the blank is- a. change its position relative to other objects.

Perception of motion can be described as a phenomenon of inferring the direction and speed and of objects, which are moving in a visual scene.

An object is said to be in motion if its position is changed with respect to objects that are present in its surrounding.

Thus, in order to sense motion of objects, humans beings are required to see an object change its position with respect to other objects.

8 0

3 years ago

An ideal gas occupies 0.4 m3 at an absolute pressure of 500 kPa. What is the absolute pressure if the volume changes to 0.9 m3 a

sveticcg [70]

Answer:

Explanation:

The new volume can be found by using the formula for Boyle's law which is

$P_1V_1 = P_2V_2$

Since we are finding the new volume

$V_2 = \frac{P_1V_1}{P_2} \\$

From the question we have

$V_2 = \frac{0.4 \times 500000}{0.9} = \frac{200000}{0.9} \\ = 222222.2222... \\ = 222222$

We have the final answer as

Hope this helps you

5 0

3 years ago

Which best explains why we are able to accelerate forward when starting to run? A) The runner's upper body quickly leans forward

Neko [114]

Answer:

D.The striking foot pushes backward against the ground. The friction with the ground provides an equal and opposite force forward

7 0

3 years ago

Read 2 more answers