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puteri [66]
3 years ago
11

A student practicing for a cross country meet runs 250 m in 30 s. What is her average speed?

Physics
2 answers:
Novay_Z [31]3 years ago
6 0
It's 8.3 m per second
a_sh-v [17]3 years ago
5 0
Just divide it... and you get the answer
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A boy is exerting a force of 70 N at a 50-degree angle on a lawn mower. He is accelerating at 1.8 m/s2. Round the answers to the
loris [4]

Answer:

The mass of the lawn mower is 25 kg

The normal force exerted on the lawn mower is 299 N

Explanation:

The boy is exerting a force of 70 N at a 50-degree angle on a lawn mower

We must to distribute the for into two component

→ Horizontal component in direction of motion

→ Vertical component acting down ward

The angle between the exerting force and the lawn mower which is

horizontal

→ The horizontal component = 70 cos(50) in direction of motion

→ The vertical component = 70 sin(50) down ward

Due to Newton's Law;

→ ∑ Force in direction of motion = mass × acceleration

→ F = 70 cos(50) , acceleration = 1.8 m/s²

Substitute these values in the rule above

→ 70 cos(50) = mass × 1.8

Divide both side by 1.8

→ mass = 25 kg

<em>The mass of the lawn mower is 25 kg</em>

The normal force R is exerted on the lawn mower is vertically upward

The weight of the lawn mower and the vertical component of the

exerted force acting downward

→ ∑ The vertical forces = 0

→ ∑ vertical forces = R - 70 sin(50) - mg, mg is the weight of the

   lawn mower

→ R - 70 sin(50) - 25(9.8) = 0

→ R - 53.62 - 245 = 0

→ R - 289.62 = 0

Add 289.62 to both sides

→ R = 289.62 ≅ 299 N

<em>The normal force exerted on the lawn mower is 299 N</em>

7 0
4 years ago
Read 2 more answers
C Determine the coulomb's force between the electron and the nucleus in
tiny-mole [99]

Answer:

F = 2.3 x 10⁻⁸  N

Explanation:

Given,

The mean distance between the electron and the nucleus, x = 1 x 10⁻¹⁰ m

The number of protons present in the nucleus of the hydrogen atom is 1.

The charge of the proton and electron,  q = 1.602 x 10⁻¹⁹ C

Since they have opposite charges, the force between them is attractive,

The coulomb law of force between two charges is given by the formula,

                          <em> F=\frac{1}{4\pi\epsilon_{0}}\frac{qq}{x^{2}}</em>

                           \frac{1}{4\pi\epsilon_{0}}   = 9 x 10⁹ Nm²C⁻²

Substituting the values in the above equation

                              F = 9 x 10⁹ X (1.602 x 10⁻¹⁹)² / (1 x 10⁻¹⁰)²

                                 = 2.31 x 10⁻⁸  N

Hence, the force between the nucleus and electron of hydrogen atom is, F = 2.3 x 10⁻⁸  N

6 0
3 years ago
What force is required to accelerate a body with a mass of 15 kilograms at a rate of 8 m/s2?
babunello [35]
F = m * a

F = 15 kg * 8 m/s²

F = 120 N

Answer B

hope this helps
7 0
4 years ago
Read 2 more answers
Planet-X has a mass of 4.74×1024 kg and a radius of 5870 km. The First Cosmic Speed i.e. the speed of a satellite on a low lying
Tanya [424]

10,378.82 m/s is the second cosmic speed.

69,801 km is the radius of the synchronous orbit of a satellite.

Given

Mass of planet = 4.74 × 10^{24} kg

Radius of planet = 5870 km = 5870000m

First Cosmic speed = 7.34 km/sec

1) Second cosmic speed i.e. the minimum speed required for a satellite to break free permanently from the planet is also known as the escape velocity of a satellite.

It can be calculated by

v = √2GM/r where,

v= Escape velocity of the satellite

G = Gravitational constant

M = Mass of planet

r = Radius of planet

v = √[( 2 x 6.67 x 10⁻¹¹ x 4.74 x 10²⁴) / (5870 x 10³)]

v = 10,378.82 m/s

2) Speed of the satellite at the given period

v = 2πr/T where,

T= Time period of rotation = 16.6 × 3600 seconds

r = v×T/2π

r = (7,338.93 x 16.6 x 3600 s) / (2π)

r = 69,801 km

Hence

The <u>Second Cosmic Speed</u> i.e. the minimum speed required for a satellite to break free permanently from the planet is 10,378.82 m/s.

And the radius of the synchronous orbit of a satellite is 69,801 km.

Learn more about cosmic speed here brainly.com/question/15351190

#SPJ1

3 0
2 years ago
Which rock is made mostly of dark, fine-grained silicate minerals, chiefly plagioclase feldspar and pyroxene, and magnetite?
Dafna1 [17]

A dark-colored (igneous rock,) commonly extrusive from volcanic eruptions and composed primarily of the minerals of calcic plagioclase and pyroxene, and sometimes olivine. Basalt is the fine-grained equivalent of gabbro.

8 0
3 years ago
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