Un cube est posé sur un plan incliné et relié à un fil attaché à un poteau.
On représente ci-dessous la situation :
{"init": {"range": [[-8.0, 8.0], [-3.0, 11.0]], "scale": [20, 20]}, "line": [[[-7.0, -2.0], [7.0, -2.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, -1.0], [7.0, -1.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, 0.0], [7.0, 0.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, 1.0], [7.0, 1.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, 2.0], [7.0, 2.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, 3.0], [7.0, 3.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, 4.0], [7.0, 4.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, 5.0], [7.0, 5.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, 6.0], [7.0, 6.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, 7.0], [7.0, 7.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, 8.0], [7.0, 8.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, 9.0], [7.0, 9.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, 10.0], [7.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[-7.0, -2.0], [-7.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[-6.0, -2.0], [-6.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[-5.0, -2.0], [-5.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[-4.0, -2.0], [-4.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, -2.0], [-3.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[-2.0, -2.0], [-2.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[-1.0, -2.0], [-1.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[0.0, -2.0], [0.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[1.0, -2.0], [1.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[2.0, -2.0], [2.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[3.0, -2.0], [3.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[4.0, -2.0], [4.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[5.0, -2.0], [5.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[6.0, -2.0], [6.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[7.0, -2.0], [7.0, 10.0], {"subtype": "segment", "stroke": "#ccc"}], [[-1.2288478807785608, 4.360193516544992], [-0.36865436423356823, 5.5890413973235535], {"subtype": "segment"}], [[-0.36865436423356823, 5.5890413973235535], [2.089041397323553, 3.8686543642335685], {"subtype": "segment"}], [[2.089041397323553, 3.8686543642335685], [1.2288478807785608, 2.6398064834550077], {"subtype": "segment"}], [[-5.0, 7.915491671180027], [-0.7987511225060645, 4.974617456934273], {"subtype": "segment"}], [[-5.0, 7.0], [-5.0, 9.0], {"subtype": "segment"}], [[5.0, 0.0], [-5.0, 7.0], {"subtype": "segment"}], [[-5.0, 0.0], [5.0, 0.0], {"subtype": "segment"}]], "arc": [[[5.0, 0.0], [1.5, 1.5], 145.00797980144134, 180.0, false, {}]], "circle": [[[0.43009675827249627, 4.114423940389281], 0.1, {"fill": "black"}]], "label": [[[3.0, -0.5], "\\alpha", "above", {}], [[-0.06990324172750373, 3.6144239403892806], "G", "above", {}]]}
On considère à présent le solide comme un point pour effectuer le bilan des forces.
On représente la situation ci-dessous :
{"init": {"range": [[-4.0, 4.564597315436242], [-7.0, 5.0]], "scale": [40, 40]}, "line": [[[-3.0, -6.0], [3.0, -6.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, -5.0], [3.0, -5.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, -4.0], [3.0, -4.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, -3.0], [3.0, -3.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, -2.0], [3.0, -2.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, -1.0], [3.0, -1.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, 0.0], [3.0, 0.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, 1.0], [3.0, 1.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, 2.0], [3.0, 2.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, 3.0], [3.0, 3.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, 4.0], [3.0, 4.0], {"subtype": "segment", "stroke": "#ccc"}], [[-3.0, -6.0], [-3.0, 4.0], {"subtype": "segment", "stroke": "#ccc"}], [[-2.0, -6.0], [-2.0, 4.0], {"subtype": "segment", "stroke": "#ccc"}], [[-1.0, -6.0], [-1.0, 4.0], {"subtype": "segment", "stroke": "#ccc"}], [[0.0, -6.0], [0.0, 4.0], {"subtype": "segment", "stroke": "#ccc"}], [[1.0, -6.0], [1.0, 4.0], {"subtype": "segment", "stroke": "#ccc"}], [[2.0, -6.0], [2.0, 4.0], {"subtype": "segment", "stroke": "#ccc"}], [[3.0, -6.0], [3.0, 4.0], {"subtype": "segment", "stroke": "#ccc"}], [[0.0, 0.0], [1.8791946308724832, 2.684563758389262], {"subtype": "segment", "arrow-end": "classic-wide-long"}], [[0.0, 0.0], [-1.8791946308724832, 1.3154362416107384], {"subtype": "segment", "arrow-end": "classic-wide-long"}], [[0.0, 0.0], [0.0, -4.0], {"subtype": "segment", "arrow-end": "classic-wide-long"}]], "circle": [[[0.0, 0.0], 0.1, {"fill": "black"}]], "label": [[[0.0, 0.0], "G", "above", {}], [[1.431136467747666, 0.9982044725766339], null], [[-1.2836747220542386, 0.16617896849394492], null], [[0.6, -2.0], null], [[1.0, -3.0], "\\overrightarrow{\\rm P}", "above", {}], [[3.9395973154362416, 0.34228187919463093], "\\overrightarrow{\\rm R}", "above", {}], [[-0.4395973154362416, 0.6577181208053692], "\\overrightarrow{\\rm T}", "above", {}]]}
Données
- - Accélération de la pesanteur : \( g = 9,81\:\text{m}\mathord{\cdot}\text{s}^{-2} \)
- - Masse du solide : \( m = 122\:\text{g} \)
En calculant graphiquement l'échelle des forces représentés, donner la valeur, en Newton (N), representée par 1
carreau.
On donnera la réponse avec \( 2 \) chiffres significatifs et suivie de l'unité qui convient.