When the logic state at this input is high, the counting stops. The first receives the rectangular pulses sent by the oscillator and the other enables the counting process when it is held at ground state. The counters have two inputs: the clock (CK) and the clock enable (CL EN). To show that the acceleration of the system is inversely proportional to its mass when the accelerating force is kept constant, we change the mass of the system by loading the glider with mass of different sizes or connecting another glider to the original. To triple the force, two discs are transferred from the glider to the hanging load, and so on.
To double the accelerating force, one disc is transferred from the glider to the hanging load. 1) Therefore, the accelerating force mg acts on a system of total mass M + 5 m. To show that the acceleration of the system is proportional to the acceleration force when the total mass is kept constant, we begin with a hanging load of mass m and add four identical metallic discs of mass m to the glider of mass M ( Fig. We consider the glider and the load as a single object, subject to the accelerating force mg. The experimental set-up consists of a glider on an air track connected by a string passing over a small pulley to a hanging load of mass m and weight mg. For this reason, when we follow the sequence outlined in PSSC, we complement the laboratory activity with an experimental demonstration that allows confirmation of the validity of Newton's second law in a quick and convincing way. Indeed, only the more attentive pupils obtain satisfactory results. The choice of stretched elastics to accelerate a cart on a level table is quite suitable as the starting point because it takes into account the intuitive notion of force related to a sensation of muscular effort but, due to the difficulty of keeping the rubber loop stretched a constant amount as the cart accelerates, the quantitative results are not always convincing. In the PSSC context, Newton's second law of motion is investigated in the laboratory, with carts, times, and a rubber loop stretched a constant amount as the unit of force. To introduce Newton's second law or concepts such as force, inertial and gravitational mass and weight, it is a common practice to use the approach offered by PSSC Physics that, according to Arons, is quite reasonable for introductory levels. Keywords: Newton's second law, measurement of time interval, measurement of acceleration, average speed. Within experimental errors, the experiments clearly show the proportionality between acceleration and force for a fixed mass and between acceleration and inverse of mass for a fixed force.
FORCES AND NEWTON II LAW EXPERIMENT HOW TO
We also show how to determine acceleration from average speeds calculated for successive time intervals of the motion measured by using several electronic counters connected to a single-crystal oscillator circuit. The experimental arrangement allows us to accelerate a glider on an air track by means of forces that are both steady and known.
We describe an experimental procedure to probe the validity of Newton's second law. Palavras-chave: segunda lei de Newton, medida de intervalo de tempo, medida de aceleração, velocidade média. Dentro dos erros experimentais, os experimentos realizados mostram claramente a proporcionalidade entre aceleração e força para uma massa constante e entre aceleração e o inverso da massa para uma força constante. Mostramos também como determinar a aceleração a partir de velocidades médias calculadas para intervalos de tempo sucessivos do movimento usando vários contadores eletrônicos conectados a um único circuito oscilador a cristal. A montagem experimental utilizada permite acelerar um carrinho sobre um trilho de ar por meio de forças constantes e conhecidas. Roberto Hessel 1 Saulo Ricardo Canola Dimas Roberto Volletĭepartamento de Física, IGCE, UNESP, Caixa Postal 178, 13506-900, Rio Claro, SP, Brazilĭescrevemos nesse trabalho um procedimento experimental para investigar a validade da segunda lei de Newton. Uma verificação experimental da segunda lei de Newton
FORCES AND NEWTON II LAW EXPERIMENT VERIFICATION
An experimental verification of Newton's second law
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