Physics: A2.5-kg box, sliding on a rough horizontal surface, has a speed of 1.2 m/s when it makes contact with a spring. the block comes to a momentary halt when the compression of the spring is 2.0 cm. the thermal energy generated by friction, from the instant the block makes contact with the spring until it comes to a momentary halt, is 0.5 j (b) what is the coefficient of kinetic friction between the box and the rough surface?

A2.5-kg box, sliding on a rough horizontal surface,

Ответ:

u8p4

09.01.2022

Physics

Explanation:

Given

mass of box =2.5 kg

speed v=1.2 m/s

compression in the spring x=2 cm

Total Initial energy $K.E.=\frac{mv^2}{2}$

$K.E.=\frac{2.5\times 1.2^2}{2}=1.8 J$

Thermal energy generated is E=0.5 J

this thermal energy is produced by friction force

Work done by Friction Force is $W=f_r\cdot s$

$f_r=\mu _k\times N$

where $\mu_k =coefficient\ of\ kinetic\ friction$

N=mg

$f_r=\mu _kmg$

$0.5=\mu _k\times 2.5\times 10\times 0.02$

$0.5=\mu _k\cdot 0.5$

$\mu _k=1$

$\mu _k=1$ contradicts the fact that friction is present because $\mu _k=1$ shows there is no friction so either surface is friction less or compression in the system should be more than 2 cm

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Ответ:

edjiejwi

21.05.2022

Physics

Answer : The correct equation that have the same coefficients order is:

$Al+FeO\rightarrow Al_2O_3+Fe$

Explanation :

Balanced chemical reaction : It is defined as the reaction in which the number of atoms of individual elements present on reactant side must be equal to the product side.

If the amount of atoms of each type on the left and right sides of a reaction differs then to balance the equation by adding coefficient in the front of the elements or molecule or compound in the chemical equation.

The coefficient tell us about that how many molecules or atoms present in the chemical equation.

The given balanced chemical reaction is,

$2CO_2+3H_2O\rightarrow C_2H_6O+3O_2$

The order of coefficients is, 2, 3, 1, 3

(a) The unbalanced chemical reaction is,

$Al+FeO\rightarrow Al_2O_3+Fe$

This reaction is an unbalanced chemical reaction because in this reaction number of aluminum and oxygen atoms are not balanced.

In order to balance the chemical equation, the coefficient '2' put before the and the coefficient '3' put before the $FeO\text { and }Fe$ and then we get the balanced chemical equation.