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2 years ago

A student lifts a 90 pound (lb) ball 4 feet (ft) in 5 seconds (s). How many joules of work has the student completed?

1 answer:

7 0

Wending your way through this question and the list of choices
is like running through a corn-maze on a moonless night with
your eyes closed.

Work = (force) x (distance)

Keeping with the units used In the question ...

   Work = (90 pounds) x (4 feet) = 360 foot-pounds .

If you want the work expressed in joules, then you need to convert
pounds and feet to newtons and meters.

   (90 pounds) x (4.448 newtons/pound) = 400.32 Newtons

   (4 feet) x (1 meter / 3.28084 feet) = 1.219 meters

Work = (force) x (distance)

      = (400.32 newtons) x (1.219 meters) = 488.1 joules .

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We want to find how much charge is on the electrons in a nickel coin. Follow this method. A nickel coin has a mass of about 4.2

monitta

Answer:

The number of atoms is $N = 4.37*10^{22} \ atoms$

Explanation:

From the question we are told that

The mass of coin is $m_n = 4.2g$

Number of atom in one mole = $n =6.02*10^{23} \ atoms$

Molar mass of nickel $M = 57.8g$

Now the relation to obtain the number of atom in the nickel coin is

$N = \frac{Mass \ of Nickel\ coin}{Molar \ mass\ of nickel } * No\ of\atoms \ in \ \ one\ mole\ of\ nickel$

$= \frac{4.2}{57.8}* 6.02*10^{23}$

$=4.37 *10^{22} atoms$

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2 years ago

Explain the relationship between velocity and acceleration. Are these scalar or vector quantities?

stiv31 [10]

A scalar is something that only has speed without a DIRECTION while a vector has direction. acceleration is a vector and mass is a scalar.

4 0

3 years ago

Read 2 more answers

a child riding a bicycle at 15 meters per second accelerates at -3,0 meters per second? for 4.0 seconds. What is the child's spe

Vika [28.1K]

Answer:

Explanation:

Given data

initital velocity u=15m/s

deceleration a=3m/s^2

time t= 4 seconds

final velocity v= ?

Applying the expression

v=u+at------1

substituting our data into the expression we have

v=15+3*4

v=15+12

v=27m/s

The velocity after 4 seconds is 27m/s

5 0

2 years ago

Brownian motion is due to:

My name is Ann [436]

Answer:

Explanation:

Brownian motion is the random movement of particles in a fluid due to their collisions with other atoms or molecules. ... Brownian motion takes its name from the Scottish botanist Robert Brown, who observed pollen grains moving randomly in water. He described the motion in 1827 but was unable to explain it.

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3 years ago

A student at another university repeats the experiment you did in lab. Her target ball is 0.860 m above the floor when it is in

dexar [7]

Answer:

K = 0.076 J

Explanation:

The height of the target, h = 0.860 m

The mass of the steel ball, m = 0.0120 kg

Distance moved, d = 1.50 m

We need to find the kinetic energy (in joules) of the target ball just after it is struck. Let t is the time taken by the ball to reach the ground.

$h=ut+\dfrac{1}{2}at^2\\\\t=\sqrt{\dfrac{2h}{g}}$