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3 years ago

How high was a brick dropped from if if falls in 2.5 seconds?

1 answer:

7 0

Using the kinematic equation d = V_0 * t + 1/2 * a * t^2, where d is height you can rewrite this to be d = 1/2*g*t^2 or 4.9t^2
g = a because this is a free fall
d = 1/2 * 9.81m/s^2 * 2.5^2
d = 30.65625m
d = 30.7m

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What is the difference between multiples and sub multiple units?

il63 [147K]

Answer:

multiple is the product of any quantity and an integer. where a sub multiple of a main unit is a unit, named by prefixing the main unit, defined as the quotient of the main unit by an integer

Explanation:

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3 years ago

What can you conclude about the direction of motion of the object after the application of the additional force?

Anna35 [415]

It will move in the direction of applied force following the law of newton that is an object is stationary until an external force is applied then it moves in direction of force

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3 years ago

Most geologists believe that the dinosaurs became extinct 65 million years ago when a large comet or asteroid struck the earth,

Alex17521 [72]

Answer:

A) 1.67 x 10 ⁻⁶ m/s

B)5.59 x $10^-^9$ %

Explanation:

Given:

d = 5.0 km,

mₐ = 2.5 x $10^1^4$ kg

u₁ = 4.0 x 10⁴ m/s

$m_n$ = 5.98 x 10 ²⁴ kg

Solve using kinetic conserved energy

mₐ x u₁ + $m_n$ x u₂ = uₓ x (mₐ + $m_n$ )

(2.5 x $10^1^4$ ) (4.0 x 10⁴ )+ (5.98 x 10 ²⁴ )(0) = uₓ x (2.5 x $10^1^4$ + 5.98 x 10 ²⁴ )

uₓ = ( 2.5 x $10^1^4$ x 4.0 x 10⁴ ) / (2.5 x $10^1^4$ + 5.98 x 10 ²⁴ )

uₓ = 1.67 x 10 ⁻⁶ m/s

B) Assuming earth radius as a R = 1.5 x 10 ¹¹ m

t = 365 days x 24 hr / 1 day x 60 minute / 1 hr x 60s / 1 minute = 31536000 s

t = 31536000 s

D = 2 π R = 2 π( 1.5 x 10 ¹¹ )

D = 9.4247 x 10 ¹¹ m

u₂ = D / t = 9.4247 x 10 ¹¹ / 31536000

u₂ = 29885.775 m/s

% = ( 1.67 x 10 ⁻⁶ m/s ) / (29885.775 m/s) x 100

% = 5.59 x $10^-^9$ %

5 0

3 years ago

James is trying to prove Newton's 2nd law of motion. He tries to move four different objects with different masses, shapes, and

STatiana [176]

The car is the heaviest object there and mass is proportional to force, meaning the heavier it is the bigger the force should be in order to move it.

8 0

3 years ago

Read 2 more answers

9) A bug of mass 0.020 kg is at rest on the edge of a solid cylindrical disk (M = 0.10 kg, R = 0.10 m) rotating in a horizontal

natima [27]

Answer:

a. ω₂ = 14rad/s

b. ∇K.E = 0.014J

c. The bug does not conserve force while moving on the disk (non-conservative force).

Explanation:

Mass of the bug (m) = 0.02kg

Mass of the cylindrical disk (M) = 0.10kg

Radius of the disk (r) = 0.10m

Initial angular velocity ω₁ = 10rad/s

final angular velocity ω₂ = ?

To calculate the new angular velocity, we relate it to the conservation of angular momentum of the system I.e when the bug was at the edge of the disk and when it is located at the centre of the disk.

I = Mr² / 2

I₁ = Mr₂ / 2 + mr²

I₁ = moment of inertia when the bug was at the edge

I₁ = [(0.10 * 0.10²) / 2 ] + (0.02 * 0.1²)

I₁ = 0.0005 + 0.0002

I₁ = 7.0*10⁻⁴kgm²

I₂ = moment of inertia when yhe bug was at the center of the disk.

I₂ = Mr² / 2

I₂ = (0.01 * 0.01²) 2

I₂ = 0.0005kgm²

for conservation of angular momentum,

I₁ω₁ = I₂ω₂

solve for ω₂

ω₂ = (I₁ * ω₁) / I₂

ω₂ = (7.0*10⁻⁴ * 10) / 5.0*10⁻⁴

ω₂ = 14 rad/s

b. the change in kinetic energy of the system is

∇K = K₂ - K₁

∇K = ½I₂*ω₂² - ½I₁*ω₁²

∇K = ½(I₂*ω₂² - I₁ω₁²)

∇K = ½[(5.0*10⁻⁴ * 14²) - (7.0*10⁻⁴ * 10²)]

∇k = ½(0.098 - 0.07)

∇K = ½ * 0.028

∇K = 0.014J

The cause of the decrease and increase in kinetic energy is because the bug uses a non-conservative force. To conserve the mechanical energy of a system, all the forces acting in it must be conservative.

The work W produced by this force brings the difference in kinetic energy of the system

W = K₂ - K₁

6 0

3 years ago