Physics, 11.11.2020 18:10 retros133

A child whose weight is 287 N slides down a 7.20 m playground slide that makes an angle of 31.0Â° with the horizontal. The coefficient of kinetic friction between slide and child is 0.120. (a) How much energy is transferred to thermal energy? (b) If she starts at the top with a speed of 0.559 m/s, what is her speed at the bottom?

Answers: 2

Show answers

Answers

Answer from: emmavaran03

$H =212.6 \ J$

$v = 7.647 \ m/s$

Explanation:

From the question we are told that

The child's weight is $W_c = 287 \ N$

The length of the sliding surface of the playground is $L = 7.20 \ m$

The coefficient of friction is $\mu = 0.120$

The angle is $\theta = 31.0 ^o$

The initial speed is $u = 0.559 \ m/s$

Generally the normal force acting on the child is mathematically represented as

=> $N = mg * cos \theta$

Note m * g = W_c

Generally the frictional force between the slide and the child is

$F_f = \mu * mg * cos \theta$

Generally the resultant force acting on the child due to her weight and the frictional force is mathematically represented as

$F =m* g sin(\theta) - F_f$

Here F is the resultant force and it is represented as F = ma

=> $ma = m* g sin(31.0) - \mu * mg * cos (31.0)$

=> $a = g sin(31.0)- \mu * g * cos (31.0)$

=> a = 9.8 * sin(31.0) - 0.120 * 9.8 * cos (31.0)

=> $a = 4.039 \ m/s^2$

F_f = 0.120 * 287 * cos (31.0)

=> $F_f = 29.52 \ N$

Generally the heat energy generated by the frictional force which equivalent tot the workdone by the frictional force is mathematically represented as

H = F_f * L

=> H = 29.52 * 7.2

=> $H =212.6 \ J$

Generally from kinematic equation we have that

v^2 = u^2 + 2as

=> v^2 = 0.559^2 + 2 * 4.039 * 7.2

=> $v = \sqrt{0.559^2 + 2 * 4.039 * 7.2}$

=> $v = 7.647 \ m/s$

Answer from: Quest

less than one you can't create energy

Answer from: Quest

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.

Another question on Physics

Physics, 22.06.2019 14:00

Me pl give an example of a collision in real life. use the law of conservation of energy to describe the transfer of momentum. be sure and discuss the momentum before and after the collision occurs. you will need at least 3 sentences to thoroughly answer this question.

Answers: 3

Answer

Physics, 22.06.2019 17:40

Aball horizontally thrown from a cliff at 8m/s

Answers: 1

Answer

Physics, 23.06.2019 02:10

How is science controlled by the governerment

Answers: 1

Answer

Physics, 23.06.2019 03:30

Select the correct lewis structure for fluorine which is group 7a element?