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3 years ago

A car moving with an intial velocity of 60m/s is brought to rest in 30 seconds calculate the acceleration

Physics

1 answer:

gregori [183]3 years ago

6 0

Answer:

a = 2 [m/s^2]

Explanation:

To solve this problem we must use the expressions of kinematics, we must bear in mind that when a body is at rest its velocity is zero.

$v_{f} = v_{i} - (a*t)$

where:

Vf = final velocity = 0

Vi = initial velocity = 60 [m/s]

a = desacceleration [m/s^2]

t = time = 30 [s]

Note: the negative sign of the above equation means that the car is slowing down, i.e. its speed decreases.

0 = 60 - (a*30)

a = 2 [m/s^2]

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What's the difference between V8 and V12 diesel engine? which one is better and why

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Answer:

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2 years ago

Wich statment belongs to Daltons atomic theroy?

lozanna [386]

Answer:

Dalton's Atomic Theory states that :-

1) All matter is made up of very tiny particles called atoms.

2) Atoms are indivisible particles , which can't be created or destroyed in a chemical reaction.

3) Atoms of a given element are identical in mass & chemical properties.

4) Atoms of very different elements have different masses & chemical properties.

5) Atoms combine in the ratio of small whole numbers to form compounds.

6) The relative number & kinds of atoms are constant in a given compound.

It's drawback's are :-

1) Atoms can be divided further into electrons , protons & neutrons.

2) According to Dalton Atomic Theory, atoms of an element are identical in mass, size and many other chemical or physical properties. But, practically we observe that atoms of several elements differ in their densities and masses. These atoms with the different masses are known as isotopes. For example, Chlorine (Cl) has 2 isotopes with the mass numbers of 35 and 37.

3) Also, according to Dalton Atomic Theory, atoms of two-different elements differ in mass, size and many other chemical or physical properties. However, this is not correct for all situations. For example, Argon (Ar) and Calcium (Ca) atoms, each have an atomic mass of 40 amu. These atoms with similar atomic masses are isobars.

4) Dalton Atomic Theory fails to explain the existence of allotropes. For example, Dalton atomic theory fails to explain the differences in properties of charcoal, graphite, and diamond (which are the allotropes of carbon).

5 0

3 years ago

Read 2 more answers

Calculate the amount of heat liberated (in kj) from 411 g of mercury when it cools from 88.0°c to 12.0°c.

Katen [24]

You should note that the melting point of mercury is -38.83°C, while the boiling point is at 356.7°C. Then, that means that there is no latent heat involved here. We only compute for the sensible heat.

ΔH = mCpΔT
The Cp of mercury is 0.14 J/g·°C
Thus,
ΔH = (411 g)(0.14 J/g·°C)(88 - 12°C)
<em>ΔH = 4,373.04 J</em>

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3 years ago

A ball is thrown upward at time t=0 from the ground with an initial velocity of 8 m/s (~ 18 mph). What is the total time it is i

evablogger [386]

Answer:

The total time it is in the air for the ball is 1.6326 s

Given:

Initial velocity = 8 $\frac{m}{s}$

To find:

the total time it is in the air = ?

Formula used:

t = $\frac{v-u}{a}$

Where t = time to reach maximum height

v = final velocity of the ball = 0 m/s

u = initial velocity of ball = 8 m/s

a = acceleration due to gravity = -9.8

Acceleration of gravity is taken as negative because ball is moving in opposite direction.

Solution:

A ball is thrown upward at time t=0 from the ground with an initial velocity of 8 m/s.

The time taken by the ball to reach the maximum height is given by,

t = $\frac{v-u}{a}$

Where t = time to reach maximum height

v = final velocity of the ball = 0 m/s

u = initial velocity of ball = 8 m/s

a = acceleration due to gravity = -9.8

Acceleration of gravity is taken as negative because ball is moving in opposite direction.

t = $\frac{0-8}{-9.8}$

t = 0.8163 s

Thus, time taken by the ball to reach the ground again = time taken to reach maximum height

So, Total time required for ball to reach ground = 2t = 2 × 0.8163

Total time required for ball to reach ground = 1.6326 s

The total time it is in the air for the ball is 1.6326 s

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3 years ago

Two ladybugs sit on a rotating disk that is slowing down at a constant rate. The ladybugs are at rest with respect to the surfac

d1i1m1o1n [39]

The two ladybugs have same rotational (angular) speed

Explanation:

The rotational (angular) speed of an object in circular motion is defined as:

$\omega=\frac{\theta}{t}$

where

$\theta$ is the angular displacement

t is the time interval considered

Here we have two ladybugs, which are located at two different distances from the axis. In particular, ladybug 1 is halfway between ladybug 2 and the axis of rotation. However, since they rotate together with the disk, and the disk is a rigid body, every point of the disk cover the same angle $\theta$ in the same time $t$ : this means that every point along the disk has the same angular speed, and therefore the two ladybugs also have the same angular speed.

On the other hand, the linear speed of the two ladybugs is different, because it follows the equation:

$v=\omega r$

where r is the distance from the axis: and since the two ladybugs are located at different $r$ , they have different linear speed.

Learn more about circular motion:

brainly.com/question/2562955

brainly.com/question/6372960

#LearnwithBrainly

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3 years ago