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3 years ago

7

You want to use a rope to pull a 10-kg box of books up a plane inclined 30∘ above the horizontal. The coefficient of kinetic fri

ction is 0.29. The rope pulls parallel to the incline.
What force do you need to exert on the rope if you want to pull the box with a constant acceleration of 0.50 m/s2 up the plane?

1 answer:

fgiga [73]3 years ago

5 0

Answer: 78.61N

Explanation

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A constant force of 120 N pushes a 55 kg wagon across an 8 m level surface. If the wagon was initially at rest, what is the fina

Illusion [34]

Answer:

The kinetic energy of the wagon is 967.0 J

Explanation:

Given that,

Force = 120 N

Mass = 55 kg

Height = 8 m

We need to calculate the kinetic energy of the wagon

Using newtons law

$F = ma$

$\dfrac{120}{55}=a$

$a =2.2\ m/s^2$

Using equation of motion

$v^2 =u^2+2as$

Where,

v = final velocity

u = initial velocity

s = height

Put the value in the equation

$v^2=0+2\times2.2\times8$

$v=5.93\ m/s$

Now, The kinetic energy is

$K.E=\dfrac{1}{2}mv^2$

$K.E=\dfrac{1}{2}\times55\times(5.93)^2$

$K.E=967.0\ J$

Hence, The kinetic energy of the wagon is 967.0 J

3 0

3 years ago

The Outlaw Run roller coaster in Branson, Missouri, features a track that is inclined at 84 ∘ below the horizontal and that span

harina [27]

Answer:

Explanation:

a)

Ff = μmgcosθ

Ff = 0.28(1600)(9.8)cos(-84)

Ff = 458.9217...

Ff = 460 N

b) ignoring the curves required at top and bottom which change the friction force significantly, especially at the bottom where centripetal acceleration will greatly increase normal forces and thus friction force.

W = Ffd

W = 458.9217(-49.4/sin(-84)

W = 22,795.6119...

W = 23 kJ

c) same assumptions as part b

The change in potential energy minus the work of friction will be kinetic energy.

KE = PE - W

½mv² = mgh - (μmgcosθ)d

v² = 2(gh - (μgcosθ)(h/sinθ))

v = √(2gh(1 - μcotθ))

v = √(2(9.8)(49.4)(1 - 0.28cot84))

v = 30.6552...

v = 31 m/s

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2 years ago

Which type of thermal energy transfer does a wrapping of cotton or plastic reduce the most, conduction, convection, radiation, t

Veseljchak [2.6K]

Answer: Thermal Energy is energy resulting from the motion of particles; It is a form of kinetic energy and is transferred as heat; Thermal Energy Transfer can occur by three methods: Conduction; Convection; Radiation; Conduction. Conduction is the transfer of thermal energy through direct contact between . particles of a substance.

Explanation:

8 0

3 years ago

When you step into a very full bath or hot tub, sometimes the water overflows. But when you step into a lake and swim, you don't

max2010maxim [7]

Answer:

This all simply due to the size of the two water bodies question and the your body size in a bath tub the water is small enough to allow the upthrust displace water out if the tub whereas in a lake the water is bigger and your body size is smaller to allow any noticeable upthrust that would cause an overflow

8 0

3 years ago

Suppose you push a hockey puck of mass m across frictionless ice for a time \Delta t, starting from rest, giving thepuck speed v

bazaltina [42]

Answer:

1. $t_2 = 2t_1$

2. $t_2 = t_1\sqrt{2}$

Explanation:

1. According to Newton's law of motion, the puck motion is affected by the acceleration, which is generated by the push force F.

In Newton's 2nd law: F = ma

where m is the mass of the object and a is the resulted acceleration. So in the 2nd experiment, if we double the mass, a would be reduced by half.

$a_1 = 2a_2$

Since the puck start from rest, in the 1st experiment, to achieve speed of v it would take t time

$t = v / a_1$

Now that acceleration is halved:

$t = \frac{v}{2a_2}$

$\frac{v}{a_2} = 2t$

You would need to push for twice amount of time $t_2 = 2t_1$

2. The distance traveled by the puck is as the following equation:

$d = at^2$

So if the acceleration is halved while maintaining the same d:

$\frac{d_1}{d_2} = \frac{a_1t_1^2/2}{a_2t_2^2/2}$

As $d_1 = d_2$ , then $d_1/d_2 = 1$ . Also $a_1 = 2a_2$

$1 = \frac{2a_2t_1^2}{a_2t_2^2}$

$t_2^2 = 2t_1^2$

$t_2 = t_1\sqrt{2}\approx 1.14t_1$

So t increased by 1.14

7 0

3 years ago