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The diagram shows some of the forces acting on a breakdown lorry towing a car. They are linked by a tow bar that experiences a tension T. D is the driving force produced by the lorry. In addition, but not shown, are forces opposing the motion of lorry and car L and C respectively y T > a) Write down an equation involving D, L, and C when the car and lorry are travelling at a constant speed. () Write down an expression for the resultant force on the lorry involving T and L when the lorry is braking with a force B