Question

• for each example, calculate the net force, direction it will move, and indicate if it is kinetic or static friction. 1. 5n 8n 2. 15 n 10 n 3. 15 n 15 n 4. 45 n 55n

Explanation:

Step1: Define net - force formula

Net force $F_{net}$ for forces acting in one - dimension is $F_{net}=\sum F$. Let right - direction be positive and left - direction be negative.

Step2: Calculate net force for example 1

$F_{1}=5N$ (right) and $F_{2} = 8N$ (left). $F_{net1}=5 - 8=- 3N$. The direction is to the left. Since the object is moving (assuming it starts moving due to the non - zero net force), it is kinetic friction.

Step3: Calculate net force for example 2

$F_{1}=15N$ (left) and $F_{2}=10N$ (right). $F_{net2}=10 - 15=-5N$. The direction is to the left. Assuming motion occurs, it is kinetic friction.

Step4: Calculate net force for example 3

$F_{1}=15N$ (right) and $F_{2}=15N$ (right). $F_{net3}=15 + 15=30N$. The direction is to the right. Assuming motion occurs, it is kinetic friction.

Step5: Calculate net force for example 4

$F_{1}=45N$ (right) and $F_{2}=55N$ (left). $F_{net4}=45 - 55=-10N$. The direction is to the left. Assuming motion occurs, it is kinetic friction.

Answer:

1. Net force: $-3N$, Direction: Left, Friction type: Kinetic
2. Net force: $-5N$, Direction: Left, Friction type: Kinetic
3. Net force: $30N$, Direction: Right, Friction type: Kinetic
4. Net force: $-10N$, Direction: Left, Friction type: Kinetic