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Maksim231197 [3]

3 years ago

14

An airplane flying at 57 m/s releases a crate of supplies that lands 821 m from where it was released. How high was the plane fl

ying?
1020 m
14.4 m
71 m
5910 m

1 answer:

Mashutka [201]3 years ago

5 0

Answer:1020

Explanation:

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A car is moving with a constant velocity of 25 m/s. Which of the following is true?

S_A_V [24]

b) the net force on the car is zero.

Explanation:

Let's analyze each option one by one:

a) the force from the engine is greater than all the forces of friction. --> FALSE. In fact, the car is moving at constant velocity: this means that its acceleration is zero,

a = 0

and so Newton's second law becomes

$\sum F = ma = 0$

where $\sum F$ is the net force on the car and m is its mass. This means that the net force on the car is zero: so, the force from the engine cannot be greater than all the forces of friction, otherwise the net force cannot be zero.

b) the net force on the car is zero. --> TRUE, for what we said at point A)

c) the inertia is changing. --> FALSE. The inertia of an object just depend on the mass and the velocity of the object: as neither the mass nor the velocity are changing in this problem, then the inertia of the car is not changing.

d) the forces of friction are proportional to the acceleration of the car. --> FALSE. Generally, the force of friction acting on an object moving on a flat surface is

$F_f = \mu mg$

where $\mu$ is the coefficient of friction, m is the mass, and g the acceleration of gravity. Therefore, the force of friction does not depend on the acceleration of the car.

e) All of the above. --> FALSE

Learn more about net force and Newton's second law:

brainly.com/question/3820012

#LearnwithBrainly

6 0

3 years ago

N which order did the events forming our solar system occur?

brilliants [131]

Answer:

The solar nebula became hot and dense because of that it pulling in more gas. This flattened into a rotating disk. It spun faster and faster, forming the Sun.

Explanation:

hope this helps

4 0

3 years ago

Read 2 more answers

Place the following steps in order for motor control. 1. Upper motor neurons stimulate lower motor neurons. 2. Sensory informati

Alla [95]

Answer:

3, 5, 1, 4, 2

Explanation:

When the body needs to move, certain muscles need to be stimulated in order to perform a certain movement. There is a process that is followed that starts with the brain sending a signal, and ends with the movement being performed by the body.

3. This is the first step, because a pathway needs to be established before any electric impulses can be sent. Hence, the upper motor neurons in the premotor cortex <u>need to choose a pathway</u> (known as a motor program).

5. This is the second step, because once a pathway has been established, a <u>signal needs to be sent</u> down that pathway. Hence, the basal nuclei enable the thalamus to stimulate the upper motor neurons to send an electrical impulse down the pathway.

1. This is the third step, because once the upper motor neurons have been stimulated, they send an electrical impulse to stimulate the lower motor neurons.

4. This is the forth step, because once the electrical impulse reaches the lower motor neurons, they pass the impulse to a certain group of skeletal muscles, causing them to contract.

2. This is the final step, because once the skeletal muscles have contracted, the <u>body has completed its movement</u>. However, once the body has moved, sensory information is relayed to the cerebellum to <u>ensure that the correct movement is made</u>, and if it needs to be adjusted, then the whole process will start again in order to correct the movement.

4 0

3 years ago

The beat your doctor listens to through a sethoscope is the sound of the four values opening

djyliett [7]

and closing .

The heart has 4 valves. They are what makes the lub-dub lub-dub sounds that can be heard from the chest.

The mitral valve is located between the left atrium and the left ventricle. It closes the left atrium to collect oxygenated blood from the lungs and opens to pass it on to the left ventricle.

The tricuspid valve is located between the right atrium and the right ventricle. It closes the right atrium to hold unoxygenated blood and opens to pass it on to the right ventricle ensuring a one way flow.

The aortic valve is located between the aorta and the left ventricle. It closes the left ventricle and opens to the aorta to pass on the oxygen-rich blood to the body.

The pulmonary valve is located between the pulmonary artery and the right ventricle. It closes off the right ventricle and opens to pass on unoxygenated blood to the lungs.

5 0

3 years ago

2.) The lob in tennis is an effective tactic when your opponent is near the net. It consists of lofting the ball over his/her he

Ratling [72]

Answer:

The minimum average speed the opponent must move so that he is in position to hit the ball is approximately 5.79 m/s

Explanation:

The given parameters of the ball are;

The initial speed of the ball = 15 m/s

The direction in which the ball is launched = 50° above the horizontal

The location of the other tennis player when the ball is launched = 10 m from the ball

The time at which the other tennis player begins to run = 0.3 seconds after the ball is launched

The height at which the ball is hit back = 2.1 m above the height from which the ball is launched

The vertical position, 'y', at time, 't', of a projectile motion is given as follows;

y = (u·sinθ)·t - 1/2·g·t²

When y = 2.1 m, we have;

2.1 = (15·sin(50°))·t - 1/2·9.8·t²

∴ 4.9·t² - (15·sin(50°))·t + 2.1 = 0

Solving with the aid of a graphing calculator function, we get;

t = 0.199776187257 s or t = 2.14525782198 s

Therefore, the ball is at 2.1 m above the start point on the other side of the court at t ≈ 2.145 seconds

The horizontal distance, 'x', the ball travels at t ≈ 2.145 seconds is given as follows;

x = u × cos(50°) × t = 15 × cos(50°) × 2.145 ≈ 20.682 m

The horizontal distance the ball travels at t ≈ 2.145 seconds, x ≈ 20.682 m

Therefore, we have;

The time the other player has to reach the ball, t₂ =2.145 s - 0.3 s ≈ 1.845 s

The distance the other player has to run, d = 20.682 m - 10 m = 10.682 m

The minimum average speed the other player has to move with, $v_s$ = d/t₂

∴ $v_s$ = 10.682 m/(1.845 s) ≈ 5.78970189702 m/s ≈ 5.79 m/s

The minimum average speed the opponent must move so that he is in position to hit the ball, $v_s$ ≈ 5.79 m/s.

5 0

3 years ago