To find the force of friction acting on a 0.5 kg toy car accelerating to the left at 3 m/s² with an applied force of 20N, we draw a free-body diagram and apply Newton's second law. The force of friction is calculated to be 18.5 N, acting in the direction opposite to the acceleration of the car.
Drawing a Free-Body Diagram (FBD) and Calculating Friction
To answer the student's question about the toy car accelerating to the left under the influence of an applied force, we must draw a free-body diagram and calculate the force of friction.
Part A: For the FBD, we would draw a rectangle to represent the toy car and label the forces acting on it. There would be an arrow pointing to the left labeled with the applied force (20 N), an arrow pointing upwards labeled with the normal force (equal to the gravitational force), an arrow pointing downwards labeled with the gravity (weight of the car, 0.5 kg × 9.8 m/s²), and an arrow pointing to the right representing the force of friction, which we have to calculate.
Part B: Using Newton’s second law, we can calculate the force of friction. We know that the net force is equal to the mass times the acceleration (F_net = m × a). Here, we have:
Mass (m) = 0.5 kg
Acceleration (a) = 3 m/s² to the left
The net force is to the left, so Newton's second law becomes:
Applied force - force of friction = mass × acceleration
20N - friction force = 0.5 kg × 3 m/s²
Solving for the friction force, we get:
Friction force = 20N - (0.5 kg × 3 m/s²)
Friction force = 18.5 N acting to the right.