The cart with a mass of 10 kg shown above moves without frictional loss on a level table. A 10-N force pulls on the cart horizontally to the right. At the same time, a 30-N force at an angle of 60° above the horizontal pulls on the cart to the left. What is the magnitude and direction of the cart's horizontal acceleration

1 answer

To determine the cart's horizontal acceleration, we need to analyze the net force acting on the cart in the horizontal direction, taking into account the two forces applied to it.

  1. Break down the forces:
    • The first force is \( F_1 = 10 , \text{N} \) to the right.
    • The second force is \( F_2 = 30 , \text{N} \) at an angle of \( 60^\circ \) above the horizontal, which we will break down into horizontal and vertical components.

The horizontal component \( F_{2,x} \) of the second force can be calculated using the cosine of the angle: \[ F_{2,x} = F_2 \cdot \cos(60^\circ) = 30 , \text{N} \cdot \cos(60^\circ) = 30 , \text{N} \cdot \frac{1}{2} = 15 , \text{N} \]

Since this force is pulling to the left, we take it as negative in the horizontal force equation: \[ F_{2,x} = -15 , \text{N} \]

  1. Calculate the net horizontal force: Now we can find the net force \( F_{\text{net}} \) acting on the cart in the horizontal direction: \[ F_{\text{net}} = F_1 + F_{2,x} = 10 , \text{N} + (-15 , \text{N}) = 10 , \text{N} - 15 , \text{N} = -5 , \text{N} \]

The negative sign indicates that the net force is directed to the left.

  1. Calculate the acceleration: Using Newton's second law \( F = ma \), where \( m \) is the mass of the cart: \[ F_{\text{net}} = m \cdot a \] \[ -5 , \text{N} = 10 , \text{kg} \cdot a \] To find the acceleration \( a \): \[ a = \frac{-5 , \text{N}}{10 , \text{kg}} = -0.5 , \text{m/s}^2 \]

  2. Interpret the result: The negative sign of the acceleration indicates that the acceleration is towards the left.

Final Answer: The magnitude of the cart's horizontal acceleration is \( 0.5 , \text{m/s}^2 \) to the left.