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Zina [86]
3 years ago
6

Imagine a rock is dropped from the top of a tall building.After 2 seconds of falling the rock is instantaneous speed In approxim

ately 20m/s
Physics
1 answer:
Fantom [35]3 years ago
8 0

This is True.

Explanation:

initial velocity= Vi=0

final velocity= V

acceleration due to gravity= 9.8 m/s²

using the kinematic equation V= Vi+gt

V=0+(9.8)(2)

V= 19.6 m/s which is approximately equal to 20 m/s

Thus after 2 seconds, the instantaneous speed of the rock is approximately 20 m/s.

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tatuchka [14]
V(voltage) = I(current)R(resistance)
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V = 15 * 0.10
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3 years ago
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Wo siblings are arguing over what way to pull a 10 kg wagon. Boris wants to pull it to the right. Boris puts 220 N of force on t
Mrrafil [7]

Answer:

a) Then net force acting on the wagon  30 [N] in a negative direction to the left

b)Acceleration of the wagon 3 m/s² in a negative direction to the left

Explanation:

The coordinates x and y show the positive direction in x-axis ( to the right) and negative direction to the left. In north-south direction positive y values are to the north and negative values to the south

The free-body diagram shows 4 forces acting

In y-axis:

The weight ( P = m*g =  10 [kg]*9,8 [m/s²] = 98 [N] negative

Normal reaction force  Fn = P = 98 [N]  positive ( surface is frictionless)

∑Fy = 0     P - Fn = 0     P = Fn  = 98 [N]

In x-axis:

Boris pulling force to the right (positive ) 220 [N]

Natasha pulling force to the left ( negative) 250 [N]

∑Fx = m*a

220 [N] - 250 [N]  = 10 Kg * a                      [N] = Kg * m /s²

-30 [kg*m/s²]  = 10 * Kg * a

-30/10  =  - 3  m/s²  = a

Sign (-) means the direction of acceleration vector is to the left (the same direction of the movement )

Then net force acting on the wagon  30 [N] in negative direction to the left

Acceleration of the wagon 3 m/s² in negative direction to the left

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3 years ago
In which of the following is positive work done by a person on a suitcase
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4 0
3 years ago
One of your summer lunar space camp activities is to launch a 1130 kg1130 kg rocket from the surface of the Moon. You are a seri
maxonik [38]

Answer:

∆U = 2.296×10^10Joules

Explanation:

Gravitational potential energy is defined as the energy possessed by an object under the influence of gravity due to its virtue of position.

Potential energy U = Fr where;

F is the force of attraction between the masses of the moon and the rocket.

r is the radius or height of the object.

From Newton's law of universal gravitation, F = GMm/r²

Potential energy U = (-GMm/r²)×r

Potential energy U = -GMm/r

The force is negative because the objects act upward.

M is the mass of the rocket

m is the mass of the moon

Gravitational potential energy possessed by the rocket

U1 = -GMm/r1

r1 is the altitude covered by the rocket

Gravitational potential energy possessed by the Moon

U2 = -GMm/(r2+r1)

r2 is the radius of the moon

Change in gravitational potential energy ∆U = U2-U1

∆U = -GMm/(r2+r1)-(-GMm/r1)

∆U = -GMm/(r2+r1) + GMm/r1

∆U = -GMm{1/(r2+r1)-1/r1}

Given

G = 6.67×10^-11m³/kgs²

M = 1130kg

m = 7.36×10²²kg

r1 = 215km = 215,000m

r2 = 1740km = 1,740,000m

∆U = -6.67×10^-11× 7.36×10²² × 1130{1/(215,000+1,740,000)-1/215000}

∆U= -55.47×10¹⁴{1/1955000-1/215000}

∆U = -55.47×10¹⁴{5.12×10^-7 - 4.65×10^-6}

∆U = -284×10^7 + 257.94×10^8

∆U = 22,954,000,000Joules

∆U = 2.296×10^10Joules

8 0
3 years ago
A plucked guitar string produces a sound wave with a wavelength of 0.15 m and a velocity of 10.5 m/s, what is the frequency of t
Leno4ka [110]
We know,
V= f× wavelength
10.5= f×0.15
f=10.5/0.15
f= 70 Hz
8 0
3 years ago
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