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aniked [119]
3 years ago
10

An object is thrown directly upwards from the ground at a velocity of 9ms. Recalling that the acceleration due to gravity is −gm

s2, find the time at which the object reaches its maximum height. What is this maximum height? Your answers should be in terms of g.
Physics
1 answer:
olga55 [171]3 years ago
6 0

Answer:

Explanation:

Given

Object is thrown with a velocity of u=9\ m/s

Acceleration due to gravity is -g (i.e. acting downward)

Vertical distance traveled by object is given by

v^2-u^2=2as  

where v=final velocity

u=initial velocity

a=acceleration

s=displacement

at maximum height final velocity is zero

0-(9)^2=2\times (-g)\times (s)

s=\frac{81}{2g}=\frac{40.5}{g}\ m

time taken to reach maximum height

using

v=u+at

0=9-gt

t=\frac{9}{g}\ s

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Awave has a period of 1. What is its frequency?
Andrei [34K]

Answer:

Frequency, f = 1 unit

Explanation:

It is given that,

Period of the wave, T = 1 unit

We need to find the frequency of the wave. There exist an inverse relationship between period and the frequency of the wave. It is given by :

T=\dfrac{1}{f}

Or

f=\dfrac{1}{T}

f=\dfrac{1}{1\ units}

f = 1 unit

So, the frequency of the wave is 1 unit. Hence, this is the required solution.

4 0
3 years ago
A 10 ohms resistor is powered by a 5-V battery. The current flowing<br> through the source is:
mario62 [17]
  • Resistance=R=10ohm
  • Voltage=V=5V
  • Current=I

Applying ohm's law

\\ \sf\longmapsto \dfrac{V}{I}=R

\\ \sf\longmapsto I=\dfrac{V}{R}

\\ \sf\longmapsto I=\dfrac{5}{10}

\\ \sf\longmapsto I=0.5A

4 0
2 years ago
A 3.5 kg object moving in two dimensions initially has a velocity v1 = (12.0 i^ + 22.0 j^) m/s. A net force F then acts on the o
lys-0071 [83]

Answer:

The work done by the force is 820.745 joules.

Explanation:

Let suppose that changes in potential energy can be neglected. According to the Work-Energy Theorem, an external conservative force generates a change in the state of motion of the object, that is a change in kinetic energy. This phenomenon is describe by the following mathematical model:

K_{1} + W_{F} = K_{2}

Where:

W_{F} - Work done by the external force, measured in joules.

K_{1}, K_{2} - Translational potential energy, measured in joules.

The work done by the external force is now cleared within:

W_{F} = K_{2} - K_{1}

After using the definition of translational kinetic energy, the previous expression is now expanded as a function of mass and initial and final speeds of the object:

W_{F} = \frac{1}{2}\cdot m \cdot (v_{2}^{2}-v_{1}^{2})

Where:

m - Mass of the object, measured in kilograms.

v_{1}, v_{2} - Initial and final speeds of the object, measured in meters per second.

Now, each speed is the magnitude of respective velocity vector:

Initial velocity

v_{1} = \sqrt{v_{1,x}^{2}+v_{1,y}^{2}}

v_{1} = \sqrt{\left(12\,\frac{m}{s} \right)^{2}+\left(22\,\frac{m}{s} \right)^{2}}

v_{1} \approx 25.060\,\frac{m}{s}

Final velocity

v_{2} = \sqrt{v_{2,x}^{2}+v_{2,y}^{2}}

v_{2} = \sqrt{\left(16\,\frac{m}{s} \right)^{2}+\left(29\,\frac{m}{s} \right)^{2}}

v_{2} \approx 33.121\,\frac{m}{s}

Finally, if m = 3.5\,kg, v_{1} \approx 25.060\,\frac{m}{s} and v_{2} \approx 33.121\,\frac{m}{s}, then the work done by the force is:

W_{F} = \frac{1}{2}\cdot (3.5\,kg)\cdot \left[\left(33.121\,\frac{m}{s} \right)^{2}-\left(25.060\,\frac{m}{s} \right)^{2}\right]

W_{F} = 820.745\,J

The work done by the force is 820.745 joules.

6 0
3 years ago
Nuclear decay occurs according to first-order kinetics. How long will it take for a sample of radon-218 to decay from 99 grams t
dedylja [7]

It will take 267 milliseconds for a sample of radon-218 to decay from 99 grams to 0. 50 grams.

We know that half life of a first order reaction is given by: t_{1/2} = 0.693/k

where k = rate of reaction

Given half life = 35 milliseconds

So from this we get k = 0.0198

Now we know that rate of first order reaction is given by: kt= 2.303 * log(R'/R)

where t= time

R'= initial amount = 99 g

R= final amount= 0.50 g

k= rate of reaction = 0.0198

Putting values of these in above equation we get t=267 milliseconds.

i.e. It will take 267 milliseconds for a sample of radon-218 to decay from 99 grams to 0. 50 grams.

To know more about radioactivity visit:

brainly.com/question/20039004

#SPJ4

4 0
1 year ago
A girl runs and cover a distance of 200m in 20 secends.The speed of the girl is ................ m/s.
Mademuasel [1]

Speed = distance/time

Speed = (200m)/(20s)

Speed = 10 m/s

4 0
3 years ago
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