Physics Chapter 13: Forces

A force is a push or pull that causes an object to move, stop, or change direction. Or anything that makes an object accelerate.

The strength of a force is measured in the SI unit called the newton (N) and is measured by using a spring balance.

<p>Mass is the amount of matter in an object, measured in grams (g) or kilograms (kg). Weight is the pull of gravity on an object, measured in newtons (N).</p> Signup and view all the answers

<p>W = mg</p> Signup and view all the answers

<p>740 N</p> Signup and view all the answers

<p>8 N</p> Signup and view all the answers

<p>56 kg</p> Signup and view all the answers

<p>Air resistance, also known as drag, is a kind of friction (a force that opposes motion) that occurs between air and another object. It's the force an object encounters as it moves through the air.</p> Signup and view all the answers

<p>Upthrust is a force that only exists in liquids. It's a push that always goes straight up, against the direction of gravity.</p> Signup and view all the answers

<p>A boat floats because the upward force of upthrust from the water balances the downward force of gravity acting on the boat. When forces are balanced, there is no net force, and the boat remains at rest.</p> Signup and view all the answers

<p>If the forces were not balanced, the boat would either sink or be pushed upwards. If the downward force of gravity is stronger than the upward force of upthrust, the boat would sink.</p> Signup and view all the answers

<p>Friction is a common force that tries to stop movement between touching surfaces. It's caused by roughness between the surfaces, creating resistance to movement.</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>The net force is 6N to the right.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>The two types of moments are clockwise and anticlockwise.</p> Signup and view all the answers

<p>The principle of moment states that an object is balanced when the clockwise moment is equal to the anticlockwise moment.</p> Signup and view all the answers

<p>The greater the force applied, the greater the moment.</p> Signup and view all the answers

<p>The greater the distance from the pivot, the greater the moment.</p> Signup and view all the answers

<p>The amount of space an object occupies</p> Signup and view all the answers

<p>The ratio of mass to volume</p> Signup and view all the answers

<p>The units for density are typically g/cm³ or kg/m³.</p> Signup and view all the answers

<p>Mass = density x volume</p> Signup and view all the answers

<p>Volume = mass/density</p> Signup and view all the answers

<p>17 kg/m³</p> Signup and view all the answers

<p>3.92 kg</p> Signup and view all the answers

<p>0.0005 m³</p> Signup and view all the answers

<p>2500 cm³</p> Signup and view all the answers

<p>Pressure is defined as the force per unit area.</p> Signup and view all the answers

<p>Pressure = Force/Area</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>4 N/m²</p> Signup and view all the answers

<p>8 m²</p> Signup and view all the answers

<p>Increasing the force on a specific area increases the pressure.</p> Signup and view all the answers

<p>Decreasing the area over which the force is applied increases the pressure.</p> Signup and view all the answers

<p>The area of contact with the ground is smaller for high heels compared to sneakers. The same force applied over a smaller area results in higher pressure.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>Gas molecules are constantly moving and colliding with the walls of their container. These collisions exert force on the walls and cause a pressure, known as gas pressure.</p> Signup and view all the answers

<p>Is the same at all locations on Earth</p> Signup and view all the answers