Question

analysis questions

1. friction: explain why the acceleration in trial 1 must be zero. how does measuring the force required for zero acceleration allow you to determine the magnitude of the force of friction (ff)?
2. relationship: based on your calculated values, as the total mass (m) of the cart increased (from trial 2 to trial 4) while the net force (fnet) was relatively constant, what happened to the predicted acceleration (acalc)?

Explanation:

Step1: Analyze zero - acceleration condition

According to Newton's second law $F_{net}=ma$. When $a = 0$, $F_{net}=0$. In the case of measuring the force for zero acceleration, the applied force must balance the force of friction. So, the magnitude of the applied force is equal to the magnitude of the force of friction $F_f$.

Step2: Consider the relationship between mass, net - force and acceleration

From Newton's second law $a=\frac{F_{net}}{m}$. If $F_{net}$ is relatively constant and $m$ (total mass of the cart) is increased, then according to the formula, the predicted acceleration $a_{calc}$ will decrease since $a$ is inversely proportional to $m$ when $F_{net}$ is constant.

Answer:

1. When acceleration is zero in Trial 1, according to Newton's second law ($F_{net}=ma$), the net - force is zero. The force required for zero acceleration is equal to the force of friction in magnitude because they balance each other.
2. As the total mass of the cart is increased while the net force is relatively constant, the predicted acceleration decreases according to the formula $a=\frac{F_{net}}{m}$.