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Hatshy [7]
3 years ago
14

A student lifts a set of books off a table and places them in the upper shelf of a book case which is 2 meters above the table.

If she applies a force of 5 newtons to lift these books, what is the work done?
0 joules
2.5 joules
-2.5 joules
10 joules
-10 joules
Physics
2 answers:
Vilka [71]3 years ago
7 0

Answer:

D.10 joules

Explanation:

AfilCa [17]3 years ago
6 0
The work done is the product between the intensity of the force applied F, the amount of the displacement d of the book and the cosine of the angle \theta between the direction of the force and the direction of the displacement:
W=Fd \cos \theta
In our problem, the student is lifting the book, so he is applying a force directed upward, and the book is moving upward, so F and d are parallel and therefore the angle is zero, so \cos \theta = \cos 0=1
Therefore, the work done is
W=Fd=(5 N)(2 m)=10 J
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Alex17521 [72]
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3 0
3 years ago
The momentum of a falling rock is found to be 200 kg m/s. What is the mass of the rock if it falls with a velocity of 5.0 m/s
Snezhnost [94]

Answer:

\boxed {\boxed {\sf 40 \ kilograms}}

Explanation:

Momentum is the product of velocity and mass. The formula is:

p=m*v

We know the rock is falling. Its momentum is 200 kilograms meters per second and its velocity is 5 meters per second. Substitute the values into the formula.

200 \ kg \ m/s = m * 5.0 \ m/s

We are solving for m, the mass. We must isolate the variable. It is being multiplied by 5 meters per second. The inverse of multiplication is division, so we divided both sides by 5.0 m/s.

\frac{200 \ kg \ m/s}{5.0 \ m/s}=\frac{ m* 5.0 \ m/s }{5.0 \ m/s}

\frac{200 \ kg \ m/s}{5.0 \ m/s}=m

The units of meters per second (m/s) cancel.

\frac{200 \ kg}{5.0 } =m

40 \ kg = m

The falling rock has a mass of <u>40 kilograms.</u>

4 0
2 years ago
What do you measure when you measure an object’s mass?
Effectus [21]

Answer:

how much space it takes up in the world

Explanation:

1) Mass is a measurement of the amount of matter something contains, while Weight is the measurement of the pull of gravity on an object. 2) Mass is measured by using a balance comparing a known amount of matter to an unknown amount of matter. Weight is measured on a scale.

3 0
3 years ago
On a snowy day, max (mass = 15 kg) pulls his little sister maya in a sled (combined mass = 20 kg) through the slippery snow. max
sesenic [268]

Work done by a given force is given by

W = F.d

here on sled two forces will do work

1. Applied force by Max

2. Frictional force due to ground

Now by force diagram of sled we can see the angle of force and displacement

work done by Max = W_1 = Fdcos\theta

W_1 = 12*5cos15

W_1 = 57.96 J

Now similarly work done by frictional force

W_2 = Fdcos\theta

W_2 = 4*5cos180

W_2= -20 J

Now total work done on sled

W_{net}= W_1 + W2

W_{net} = 57.96 - 20 = 37.96 J

7 0
3 years ago
a block that is 80 degrees is places next to a 20 degree block. the warmer block heats the cooler block by the process of... A)c
11Alexandr11 [23.1K]
Answer: option B: conduction.

Conduction is the heat transfer that happens between two bodies in direct contact, due to the collision of the molecules, atoms and electrons within the body (microscopical level).
6 0
3 years ago
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