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Sphinxa [80]
3 years ago
11

A ball dropped from rest falls freely until it hits the ground with a speed pf 20 m/s. The time during with the ball is in free

fall is approximately
Physics
1 answer:
saul85 [17]3 years ago
5 0

Answer:

\large \boxed{\text{2.0 s}}

Explanation:

\begin{array}{rcl}v & = & gt\\\text{20 m$\cdot$s}^{-1} & = & \text{9.807 m$\cdot$ s}^{-2} \times t\\t & = & \dfrac{20}{9.807 \text{ s}^{-1}}\\\\& = & \textbf{2.0 s}\\\end{array}\\\text{The ball is in free fall for $\large \boxed{\textbf{2.0 s}}$}

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How fast would 0.145 kg baseball have to go to have a kinetic energy of 88.7 J?
Sergeu [11.5K]

Answer:

Correct answer: v = 34.98 m/s

Explanation:

The kinetic energy formula is Ek = m v²/2 => v = √2Ek/m

v = √2 · 88.7 / 0.145 = 34.98 m/s

God is with you!!!

7 0
3 years ago
1).which of the following describes the interaction between a south pole and a north pole of a magnet
kumpel [21]

1) a) attract

The magnetic force between two magnetic poles is attractive for two unlike poles and repulsive for two like poles. Therefore we have:

1- For two north poles, the force between them is repulsive

2- For two south poles, the force between them is repulsive

3- For a north pole and a south pole, the force between them is attractive

In this problem, we are in the situation described in 3), so the force between the poles is attractive.

2) a) motion of electrons

While electric fields are produced by static electric charges, magnetic fields are produced by charges in motion (currents). In particular, a current in a wire (where a current is simply the motion of electrons inside the wire) produces a magnetic field whose intensity is

B=\frac{\mu_0 I}{2 \pi r}

where

I is the current in the wire

r is the radial distance from the wire

And the direction of the field lines are such that the field form concentric circles around the wire.

6 0
3 years ago
An artificial satellite of mass 900kg Is launched at a speed of 11,000 m/s from its launching station. How much is the kinetic e
Marina CMI [18]

Answer:

KE = 54450 J

Explanation:

Data:

  • m = 900 kg
  • v = 11.000 m/s
  • KE = ?

Use the formula:

  • \boxed{\bold{K_{E}=\frac{m*(v)^{2}}{2}}}

Replace and solve:

  • \boxed{\bold{K_{E}=\frac{900\ kg*(11.000\frac{m}{s})^{2}}{2}}}
  • \boxed{\bold{K_{E}=\frac{900\ kg*121\frac{m^{2}}{s^{2}}}{2}}}
  • \boxed{\bold{K_{E}=\frac{108900\ J}{2}}}
  • \boxed{\boxed{\bold{K_{E}=54450\ J}}}

A kinetic energy of <u>54450 Newtons</u> is imparted to it.

Greetings.

6 0
3 years ago
To review the solution to a similar problem, consult Interactive Solution 1.43. The magnitude of a force vector is 87.4 newtons
trasher [3.6K]

Answer:

(a) 34.4°

(b) 49.4 N

Explanation:

(a) From the diagram,

Amgle between the x axis can be calculated as,

cosΘ = adjacent/hypoteneous

cosΘ = 72.1/87.4

cosΘ = 0.8249

Θ = cos⁻¹(0.8249)

Θ = 34.4°.

Hence the angle between the x axis is 34.4°

(b) To find the component along the y axis we make use of pythagoras theorem.

a² = b²+c²................... Equation 1

Where a = 87.4 N, b = 72.1 N, c = y.

Substitute  these values into equation 1

87.4² = 72.1² + y²

y² = 87.4²-72.1²

y² = 2440.35

y = √(2440.35)

y = 49.4 N

7 0
3 years ago
A train brakes from 25 m/s to rest in 30 sec. What is its deceleration?
givi [52]

Answer:

a= -0.83m\s^2

Explanation:

a = v \ t

a = -25 \ 30 = -0.833 m\s^2

the object is slowing down 0.83 meter every second

8 0
3 years ago
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