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3 years ago

PLEASE HELP!! PHYSICS QUIZ!

Physics

2 answers:

diamong [38]3 years ago

5 0

Answer: True

Explanation: A projectile is launched at certain angle with the horizontal. Hence, its equation of motion can be described using vertical and horizontal components. Therefore, the statement is true.

Answer: False

Explanation:

The shape of the trajectory of a projectile is parabola. Hence, the given statement is false.

Answer: A) constant

Explanation: During the course of trajectory, the horizontal component of the velocity is constant. There is no external force acting in the horizontal direction. In the vertical direction, acceleration due to gravity acts which increases the vertical component of velocity. Hence, the correct option is A.

Dmitriy789 [7]3 years ago

4 0

1). Technically false if you're persnickety about your words. But this quiz wants you to say 'True'.

The projectile doesn't have vertical and horizontal components. But if the projectile is moving, then its displacement, velocity, and acceleration can have vertical and horizontal components.

2). This one's false. The shape of a projectile's trajectory is a parabola. (Unless the projectile is moving fast enough to be in a stable orbit. THEN its path is an ellipse.)

3). During the time the projectile is flying, the horizontal component of its velocity is constant IF THERE'S NO AIR RESISTANCE.

If there IS air resistance, then the horizontal component of velocity is decreasing.

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A paragraph that can serve the specific purpose of creating a special effect within the essay is called?

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Its b.functional paragraph because writers use this for interest presents and special effects

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2 years ago

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At divergent boundaries, hot mantle rock rises and _____ occurs.

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When rock rises, they decrease in pressure causes hot mantle rock to melt and form magma. In plate tectonics, divergent boundaries occur when plates pull apart.

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2 years ago

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A plastic film moves over two drums. During a 4-s interval the speed of the tape is increased uniformly from v0 = 2ft/s to v1 =

Ratling [72]

Answer:

Question 1)

a) The speed of the drums is increased from 2 ft/s to 4 ft/s in 4 s. From the below kinematic equations the acceleration of the drums can be determined.

$v_1 = v_0 + at \\4 = 2 + 4a\\a = 0.5~ft/s^2$

This is the linear acceleration of the drums. Since the tape does not slip on the drums, by the rule of rolling without slipping,

$v = \omega R\\a = \alpha R$

where α is the angular acceleration.

In order to continue this question, the radius of the drums should be given.

Let us denote the radius of the drums as R, the angular acceleration of drum B is

α = 0.5/R.

b) The distance travelled by the drums can be found by the following kinematics formula:

$v_1^2 = v_0^2 + 2ax\\4^2 = 2^2 + 2(0.5)x\\x = 12 ft$

One revolution is equal to the circumference of the drum. So, total number of revolutions is

$x / (2\pi R) = 6/(\pi R)$

Question 2)

a) In a rocket propulsion question, the acceleration of the rocket can be found by the following formula:

$a = \frac{dv}{dt} = -\frac{v_{fuel}}{m}\frac{dm}{dt} = -\frac{13000}{2600}25 = 125~ft/s^2$

b) $a = -\frac{v_{fuel}}{m}\frac{dm}{dt} = - \frac{13000}{400}25 = 812.5~ft/s^2$

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3 years ago

A pulsar is a rapidly rotating neutron star. The Crab nebula pulsar in the constellation Taurus has a period of 33.5\times 10^{-

joja [24]

Answer:

$5.25\cdot 10^{40} kg m^2/s$

Explanation:

The angular momentum of the pulsar is given by:

$L=m\omega r^2$

where

$m=2.8\cdot 10^{30} kg$ is the mass of the pulsar

$r = 10.0 km = 1\cdot 10^4 m$ is the radius

$\omega$ is the angular speed

Given the period of the pulsar, $T=33.5\cdot 10^{-3} s$ , the angular speed is given by

$\omega=\frac{2\pi}{T}=\frac{2 \pi}{33.5\cdot 10^{-3}s}=187.5 rad/s$

And so, the angular momentum is

$L=m\omega r^2=(2.8\cdot 10^{30}kg)(187.5 rad/s)(1\cdot 10^4 m)^2=5.25\cdot 10^{40} kg m^2/s$

8 0

3 years ago

The winch takes in cable at the constant rate of 130 mm/s. if the cylinder mass is 115 kg, determine the tension in cable 1. neg

nikitadnepr [17]

By applying Newton's second law of motion;

ma = mg - T

Where,
m = mass; a = downward accelerations (+ve value) or upward acceleration (-ve value); g = gravitational acceleration; T = tension.

For the current case, the velocity is constant therefore,
a = 0

Then,
0 = mg - T
T = mg = 115*9.81 = 1128.15 N

Tension in the cable is 1128.15 N.

8 0

3 years ago