Is better to run or walk when it is raining?

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:

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6 0

3 years ago

a_______ is a region where the magnetic fields of a large number of atoms are lined up parallel to a magnets field.

patriot [66]

Answer:

Magnetic Domain

Explanation:

5 0

3 years ago

Read 2 more answers

Static cling makes your clothes stick together. what causes this to happen? 1. external forces to the clothes 2. forces of natur

djyliett [7]

This phenomenon is as a result of static friction created by the tumbling clothes. Static friction results from the rubbing together of two or mores objects or body and electrons are stripped from one surface of the clothes more than the other. This creates an electrostatic force of attractions between the positive charges on one cloth and the negative charges on the other cloth.(unlike charges attract).

5 0

3 years ago

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A bicycle tire of a radius of 0.44 m has a piece of gum stuck on its rim. What is the angle through which the tire rotates when

Karolina [17]

Based on the calculations, the angle through which the tire rotates is equal to 4.26 radians and 244.0 degrees.

<h3>How to calculate the angle?</h3>

In Physics, the distance covered by an object in circular motion can be calculated by using this formula:

S = rθ

<u>Where:</u>

r is the radius of a circular path.

θ is the angle measured in radians.

S is the distance.

Substituting the given parameters into the formula, we have;

1.87 = 0.44 × θ

θ = 1.87/0.44

θ = 4.26 radians.

Next, we would convert this value in radians to degrees:

θ = 4.26 × 180/π

θ = 4.26 × 180/3.142

θ = 244.0 degrees.

Read more on radians here: brainly.com/question/19758686

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6 0

2 years ago

A tennis ball connected to a string is spun around in a vertical, circular path at a uniform speed. The ball has a mass m = 0.15

Oksanka [162]

1) 5.5 N

When the ball is at the bottom of the circle, the equation of the forces is the following:

$T-mg = m\frac{v^2}{R}$

where

T is the tension in the string, which points upward

mg is the weight of the string, which points downward, with

m = 0.158 kg being the mass of the ball

g = 9.8 m/s^2 being the acceleration due to gravity

$m \frac{v^2}{R}$ is the centripetal force, which points upward, with

v = 5.22 m/s being the speed of the ball

R = 1.1 m being the radius of the circular trajectory

Substituting numbers and re-arranging the formula, we find T:

$T=mg+m\frac{v^2}{R}=(0.158 kg)(9.8 m/s^2)+(0.158 kg)\frac{(5.22 m/s)^2}{1.1 m}=5.5 N$

2) 3.9 N

When the ball is at the side of the circle, the only force acting along the centripetal direction is the tension in the string, therefore the equation of the forces becomes:

$T=m\frac{v^2}{R}$

And by substituting the numerical values, we find

$T=(0.158 kg)\frac{(5.22 m/s)^2}{1.1 m}=3.9 N$

3) 2.3 N

When the ball is at the top of the circle, both the tension and the weight of the ball point downward, in the same direction of the centripetal force. Therefore, the equation of the force is

$T+mg=m\frac{v^2}{R}$

And substituting the numerical values and re-arranging it, we find

$T=m\frac{v^2}{R}-mg=(0.158 kg)\frac{5.22 m/s)^2}{1.1 m}-(0.158 kg)(9.8 m/s^2)=2.3 N$

4) 3.3 m/s

The minimum velocity for the ball to keep the circular motion occurs when the centripetal force is equal to the weight of the ball, and the tension in the string is zero; therefore:

$T=0\\mg = m\frac{v^2}{R}$

and re-arranging the equation, we find

$v=\sqrt{gR}=\sqrt{(9.8 m/s^2)(1.1 m)}=3.3 m/s$

7 0

3 years ago