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3 years ago

What is Newton's first law of motion

1 answer:

8 0

Newtons 1st law of motion is law of inertia and this law is either an object at rest stays at rest or an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

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Friction occurs when microscopic hills and valleys stick together<br><br> true or false

Reika [66]

Answer:

true

Explanation:

Friction occurs because no surface is perfectly smooth. Rougher surfaces have more friction between them. Heavier objects also have more friction because they press together with greater force. Friction produces heat because it causes the molecules on rubbing surfaces to move faster and have more energy.

4 0

3 years ago

Read 2 more answers

A stone is thrown downward with a speed of 8 m/s from a height of 14 m. (acceleration due to gravity: 10 m/s2) What is the speed

max2010maxim [7]

Answer:

The speed of the stone just before it hits the ground is 18.54 m/s

Explanation:

Given that,

Initial speed of the stone, u = 8 m/s

The stone is thrown downward from a height of 14 m

We need to find the speed of the stone just before it hits the ground. It can be calculated using third equation of motion as :

$v^2-u^2=2ah$

v is the speed of the stone just before it hits the ground

$v^2=2ah+u^2$

$v^2=2\times 10\times 14+(8)^2$

v = 18.54 m/s

So, the speed of the stone just before it hits the ground is 18.54 m/s. Hence, this is the required solution.

6 0

3 years ago

A small dog is trained to jump straight up a distance of 1.2 m. How much kinetic energy does the 7.2-kg dog need to jump this hi

LUCKY_DIMON [66]

Answer:84.672 joules.

Explanation:

1) Data:

m = 7.2 kg
h = 1.2 m
g = 9.8 m / s²

2) Physical principle

Using the law of mechanical energy conservation principle, you have that the kinetic energy of the dog, when it jumps, must be equal to the final gravitational potential energy.

3) Calculations:

The gravitational potential energy, PE, is equal to m × g × h

So, PE = m × g × h = 7.2 kg × 9.8 m/s² × 1.2 m = 84.672 joules.

And that is the kinetic energy that the dog needs.

8 0

4 years ago

A medicine ball has a mass of 6 kg and is thrown with a speed of 4 m/s. What is its kinetic energy?

zhenek [66]

Answer:

$\boxed{\sf Kinetic \ energy \ (KE) = 48 \ J}$

Given:

Mass (m) = 6 kg

Speed (v) = 4 m/s

To Find:

Kinetic energy (KE)

Explanation:

Formula:

$\boxed{ \bold{\sf KE = \frac{1}{2} m {v}^{2} }}$

Substituting values of m & v in the equation:

$\sf \implies KE = \frac{1}{2} \times 6 \times {4}^{2}$

$\sf \implies KE = \frac{1}{ \cancel{2}} \times \cancel{2} \times 3 \times 16$

$\sf \implies KE =3 \times 16$

$\sf \implies KE = 48 \: J$

6 0

4 years ago

9. You drive a car from Milwaukee to Chicago, which is a distance of 150km and it takes you 95

Katena32 [7]

For this case we have to, by definition:

$v = \frac {x} {t}$

Where:

v: It's the velocity

x: It is the distance traveled

t: It is the time spent

1 hour equals 60 minutes and 1 minute equals 60 seconds.

On the other hand:

1 kilometer equals 1000 meters

So: $\frac {150} {95} \frac{km} {min} * \frac {1} {60} \frac {min} {sec} * \frac {1000} {1} \frac {m} {km} = \frac {150 * 1000} {95 * 60} \frac {m} {sec} = \frac {15000} {5700} \frac {m} {sec} = 2.63 \frac {m} {sec}$

On the other hand: $\frac {150} {95} \frac{km} {min} * \frac {60} {1} \frac {min} {hr} = \frac {150 * 60} {95} \frac {km} {h} = 94.74 \frac {km} {h}$

ANswer:

$2.63 \frac {m} {sec}\\94.74 \frac {km} {h}$

8 0

3 years ago

What is Newton's first law of motion​

What is Newton's first law of motion