4.6 Problem-Solving Strategies

A toboggan with two riders has a total mass of 85.0 kg. A third person is pushing with a force of 42.5 N in the direction of motion on a toboggan moving on a sloped surface at the top of a hill that has a downward angle of 15°. The force of friction on the toboggan is 31.0 N. Which statement describes an accurate free-body diagram to represent the situation?

1. An arrow of magnitude 10.5 N points dow…

Which statement is true about drawing free-body diagrams?

1. Drawing a free-body diagram should be the last step in solving a problem about forces.
2. Drawing a free-body diagram helps you compare forces quantitatively.
3. The forces in a free-body diagram should always balance.
4. Drawing a free-body diagram can help you determine the net force.

A freight train consists of two $8.00 \times 10^{4} -\text{kg}$ engines and 45 cars with average masses of $5.50 \times 10^{4} \text{kg}$ . (a) What force must each engine exert backward on the track to accelerate the train at a rate of $5.00 \times \text{10}^{–\text{2}} \text{ m}/\text{s}^{2}$ if the force of friction is $7 . \text{50} \times \text{10}^{5} \text{ N}$, assuming the engines exert identical forces? This is not a large frictional force for such a massive system. Rolling friction for trains is small, and consequently trains are very energy-e…

A 1100-kg car pulls a boat on a trailer. (a) What total force resists the motion of the car, boat, and trailer, if the car exerts a 1900-N force on the road and produces an acceleration of $0 . \text{550 m}/\text{s}^{2}$? The mass of the boat plus trailer is 700 kg. (b) What is the force in the hitch between the car and the trailer if 80% of the resisting forces are experienced by the boat and trailer?

Two children pull a third child on a snow saucer sled exerting forces $\textbf{F}_{1}$ and $\textbf{F}_{2}$ as shown from above in the figure. Find the acceleration of the 49.00-kg sled and child system. Note that the direction of the frictional force is unspecified; it will be in the opposite direction of the sum of $\textbf{F}_{1}$ and $\textbf{F}_{2}$.