Respuesta :
Answer
given,
mass of the block = 200 g = 0.2 Kg
Velocity at A = 0 m/s
Velocity at B = 8 m/s
slide to the horizontal distance = 10 m
height of the block be = 4 m
potential energy of the block
P = m g h
P = 0.2 x 9.8 x 4
P =7.84 J
kinetic energy
[tex]KE = \dfrac{1}{2}mv^2[/tex]
[tex]KE = \dfrac{1}{2}\times 0.2 \times 7.84^2[/tex]
[tex]KE =6.14 J[/tex]
Work = P - KE
work = 7.84 - 6.14
work = 1.7 J
b) v² = u² + 2 a s
0 = 8² - 2 x a x 10
a = 3.2 m/s²
ma - μ mg = 0
[tex]\mu = \dfrac{a}{g}[/tex]
[tex]\mu = \dfrac{3.2}{9.8}[/tex]
[tex]\mu = 0.327[/tex]
The work done by friction along the horizontal surface is 6.4 J, and the coefficient of kinetic friction along the horizontal surface is 0.327.
- The given parameters;
- mass of the rock, m = 200 g = 0.2 kg
- final speed of the block, v = 8 m/s
- distance traveled, s = 10 m
The normal force on the block is calculated as;
[tex]F_n = mg[/tex]
[tex]F_n = 0.2 \times 9.8\\\\F_n = 1.96 \ N[/tex]
The acceleration of the block over the given distance is calculated as;
[tex]v^2 = u^2 + 2as\\\\v^2 = 0 + 2as\\\\v^2 = 2as\\\\a = \frac{v^2}{2s} \\\\a = \frac{(8)^2}{2\times 10} \\\\a = 3.2 \ m/s^2[/tex]
The coefficient of kinetic friction is calculated as;
a = μg
[tex]\mu_k = \frac{a}{g} \\\\\mu_k =\frac{3.2}{9.8} \\\\\mu_k = 0.327[/tex]
The frictional force along the surface is calculated as;
[tex]F_k = \mu_k F_n\\\\F_k = 0.327\times 1.96\\\\F_k = 0.64 \ N[/tex]
The work done by friction along the horizontal surface is calculated as;
[tex]Work-done = F_k \times d\\\\Work-done = 0.64 \times 10\\\\Work-done = 6.4 \ J[/tex]
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