6.3. Practice Sets: Introduction to Forces; Newton’s Laws
Chapter Equations
[latex]a = \frac{F_{\text{net}}}{m}[/latex] (1)
[latex]F_g = m \times g[/latex] (2)
Try It!
- An object moving at constant speed is subjected to a net force equal to: ?
- A wagon is pulled by a force making a [latex]30^\circ[/latex] angle with the horizontal. The net force that creates the horizontal acceleration of the wagon is:
- The pulling force
- The x component of the pulling force
- The y component of the pulling force
- It is known that the acceleration due to gravity on the Moon is about 6 times smaller than that on Earth. A [latex]65\,\text{kg}[/latex] astronaut will have:
- The same mass on the Moon
- The same weight on the Moon
Practice
- It takes [latex]4500\,\text{N}[/latex] to accelerate a car at a rate of [latex]3.42 \, \text{m/s}^2[/latex]. What is the mass of the car?
Answer:[latex]1316 \text{ kg}[/latex] - A Ferrari accelerates from 0 to [latex]100.0\,\text{km/h}[/latex] in [latex]4.80\,\text{s}[/latex]. What force (in N) does a passenger of mass [latex]68.0 \, \text{kg}[/latex] experience during acceleration?
Answer:[latex]394 \text{ N}[/latex] - A child pulls on a wagon handle at an angle [latex]37^\circ[/latex] above the horizontal with a force of [latex]45\,\text{N}[/latex]. If the wagon accelerates at [latex]8.1 \, \text{m/s}^2[/latex] horizontally, what is the mass of the wagon? Assume friction is negligible.
Answer:[latex]4.4 \text{ kg}[/latex]
Challenge Questions
Try out the two challenge questions below. Turn the card to see the answer. Click on the “next” arrow to progress to the next question.
Text Version of the Challenge Question(s)
- 1. A horizontal force of 10 N is applied to a 30 kg cart on a level floor. How far will it move in 3.0 s, starting from rest? Ignore friction.
Answer: [latex]1.50~\text{m}[/latex]
- 2. A horizontal force of 10 N is applied to a 30 kg cart on a level floor. How far will it move in 3.0 s if 30 N are first added to the cart?
Answer: [latex]1.36~\text{m}[/latex]
