4 Newton's Laws of Motion - BC Science Physics 11
4 Newton's Laws of Motion - BC Science Physics 11
4 Newton's Laws of Motion - BC Science Physics 11
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Quick Check<br />
1. A single engine plane has a mass <strong>of</strong> 1500 kg and acceleration <strong>of</strong> 0.400 m/s 2 . What is the thrust, or unbalanced<br />
force, from the engine?<br />
2. What is the mass <strong>of</strong> a rocket that accelerates at 2.0 m/s 2 and has a thrust <strong>of</strong> 25 000 N?<br />
3. Find the acceleration <strong>of</strong> a passenger jet that has a mass <strong>of</strong> 250 000 kg and an engine thrust that provides an<br />
unbalanced force <strong>of</strong> 50 000 N.<br />
Multiple Forces<br />
The example and problems in the Quick Check above involve only one unbalanced force.<br />
In other situations, like Sample Problem 4.2.1 below, there are more forces to consider.<br />
Remember that, in these problems, it is important to identify the forces that<br />
create the unbalanced force. Figure 4.2.1 shows four different forces acting on a block.<br />
The two vertical forces are the force <strong>of</strong> gravity and the normal force (the force exerted by<br />
the floor on the block). The two horizontal forces are the applied force and the force <strong>of</strong><br />
friction.<br />
The two vertical forces balance each other because the force <strong>of</strong> gravity and the<br />
normal force equal each other in size and act in opposite directions. The unbalanced force<br />
is the difference between the applied force and the friction force opposing the applied<br />
force.<br />
<strong>11</strong>0 Chapter 4 Newton’s <strong>Laws</strong> <strong>of</strong> <strong>Motion</strong> © Edvantage Interactive 2012 ISBN 978-0-9864778-3-6
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