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2 years ago

Does a car that is slowing down always have a negative acceleration explain

Physics

1 answer:

Zina [86]2 years ago

4 0

No, because sometimes you have to stop at stop signs and stop lights.

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Which of the following is likely to contribute to geological events that take place on Earth?

Dennis_Churaev [7]

Crust sitting on top of Milton rock of the mantle

5 0

3 years ago

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What are the three most abundant gases in the dry atmosphere?

Anastaziya [24]

Answer:

Nitrogen, Oxygen, Argon.

Explanation:

The three (3) most abundant gases in the dry atmosphere are"

- Nitrogen

- Oxygen

- Argon

These are not the only components of dry air. Dry atmosphere is made up of:

- 78.09% Nitrogen;

- 20.95% Oxygen;

- 0.93% Argon;

- 0.04% Carbon dioxide;

- Other gases

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2 years ago

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Two objects, one having three times the mass of the other, are dropped from the same height in a vacuum. At the end of their fal

gogolik [260]

Answer:

Two objects will have the equal velocities but the forces on both of them will not be equal. The equal velocities of these objects are due to their equal acceleration.

Explanation:

From the newton's equation

$v^{2} -u^{2} = 2as$

so here we can say that velocity does not depends on the mass.

The acceleration of both objects will be same but not the forces because

F = Ma

As the force is depending on the mass so it will not be the same for both objects.

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2 years ago

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A 3.45-kg centrifuge takes 100 s to spin up from rest to its final angular speed with constant angular acceleration. A point loc

Dafna11 [192]

Answer:

(a) 18.75 rad/s²

(b) 14920.78 rev

Explanation:

(a)

First we find the acceleration of the centrifuge using,

a = (v-u)/t......................... Equation 1

Where v = final velocity, u = initial velocity, t = time.

Given: v = 150 m/s, u = 0 m/s ( from rest), t = 100 s

Substitute into equation 1

a = (150-0)/100

a = 1.5 m/s²

Secondly we calculate for the angular acceleration using

α = a/r..................... Equation 2

Where α = angular acceleration, r = radius of the centrifuge

Given: a = 1.5 m/s², r = 8 cm = 0.08 m

substitute into equation 2

α = 1.5/0.08

α = 18.75 rad/s²

(b)

Using,

Ф = (ω'+ω).t/2........................... Equation 3

Where Ф = number of revolution of the centrifuge, ω' = initial angular velocity, ω = Final angular velocity.

But,

ω = v/r and ω' = u/r

therefore,

Ф = (u/r+v/r).t/2

where u = 0 m/s (at rest), = 150 m/s, r = 0.08 m, t = 100 s

Ф = [(0/0.08)+(150/0.08)].100/2

Ф = 93750 rad

If,

1 rad = 0.159155 rev,

Ф = (93750×0.159155) rev

Ф = 14920.78 rev

6 0

3 years ago

A sled of mass 80 kg starts from rest and slides down an 18° incline 90 m long. It then travels for 20 m horizontally before sta

yaroslaw [1]

Answer:

net work done by friction = - 2205 J

Explanation:

given,

mass of sled = 80 kg

slide down at an angle of 18°

length = 90 m

travel horizontally = 20 m before starting back up a 16° incline.

net work = ?

$h_i = initial\ height$

$h_i = L_i Sin 18^0$

$h_i = 90 sin 18^0$

$h_i = 27.81\ m$

$h_f = Final\ height$

$h_f = L_f Sin 16^0$

$h_f = 90 sin 16^0$

$h_f =24.81\ m$

net work done by friction = change in potential energy

= mg (h_f - h_i)

= (75) (9.8) (- 27.81 + 24.81)

net work done by friction = - 2205 J

7 0

2 years ago