Question

по поверхні рівномірно тягнуть брусок масою 4 кг., прикладаючи силу 8Н. визначити коефіцієнт тертя. Яку силу потрібно буде прикласти, якщо на брусок поставити тягарець масою 3кг.​

Answer 1

Ответ: 0,2; 14Н

Объяснение:

Дано:

m1=4кг

F1=8Н

Δm=3кг

-----------

μ-?

F2-?

При равномерном перемещении тела, сила тяги равна силе сопротивления:

F1=F1сопр=8Н

Силу сопротивления находим по формуле:

Fсопр = Fт*μ=mgμ

Отсюда μ=Fcопр/(mg)=8/(4*10)=0,2

F2=Fт2*μ=(m1+Δm)*g*μ=(4+3)*10*0,2=14Н

Answer 2

Calculation of Coefficient of Friction and Required Force

To calculate the coefficient of friction and the force required when a 3kg weight is placed on the block, we can use the following steps:

1. Calculate the Coefficient of Friction: - The coefficient of friction can be calculated using the formula: \[ \text{Coefficient of Friction} = \frac{\text{Force of Friction}}{\text{Normal Force}} \] - The force of friction can be calculated using the formula: \[ \text{Force of Friction} = \text{Applied Force} - \text{Force Due to Weight} \] - The normal force can be calculated using the formula: \[ \text{Normal Force} = \text{Weight} + \text{Force Due to Weight} \]

2. Calculate the Required Force with the Additional Weight: - Once the coefficient of friction is determined, the required force can be calculated using the formula: \[ \text{Required Force} = \text{Force Due to Weight} + (\text{Coefficient of Friction} \times \text{Normal Force}) \]

Calculation Steps

1. Calculate the Coefficient of Friction: - The force of friction can be calculated as follows: \[ \text{Force of Friction} = 8N - (4kg \times 9.8m/s^2) \] \[ \text{Force of Friction} = 8N - 39.2N = -31.2N \] - The normal force can be calculated as follows: \[ \text{Normal Force} = 4kg \times 9.8m/s^2 + 3kg \times 9.8m/s^2 = 39.2N + 29.4N = 68.6N \] - Therefore, the coefficient of friction can be calculated as: \[ \text{Coefficient of Friction} = \frac{-31.2N}{68.6N} \] \[ \text{Coefficient of Friction} \approx -0.454 \]

2. Calculate the Required Force with the Additional Weight: - The force due to the weight of the 3kg mass is: \[ \text{Force Due to Weight} = 3kg \times 9.8m/s^2 = 29.4N \] - Using the coefficient of friction calculated earlier, the required force can be calculated as: \[ \text{Required Force} = 29.4N + (-0.454 \times 68.6N) \] \[ \text{Required Force} \approx 29.4N - 31.1N \] \[ \text{Required Force} \approx -1.7N \]

Conclusion

When a 3kg weight is placed on the block, the calculated coefficient of friction is approximately -0.454. The negative sign indicates that the force of friction opposes the applied force. The required force to move the block with the additional weight is approximately -1.7N.