A ball is hanging from a long string that is tied to the ceiling of a train car traveling eastward on horizontal tracks. An observer inside the train car sees the ball hang motionless. Draw a clearly labeled free-body diagram for the ball if (b) the train is speeding up uniformly. Is the net force on the ball zero in either case? Explain.

The figure shows all the forces acting on an object. Which arrow could represent the acceleration of that object?

The figure shows all the forces acting on an object. What can you tell about the velocity of the object at this instant?

Nick is pulling a $20\mathrm{kg}$ crate across a horizontal floor with a rope angled 30° above the horizontal. The coefficients of kinetic and static friction are 0.2 and 0.3 respectively. If the crate is moving at a constant speed, what is the tension in the rope?

Crates A and B sit at rest side by side on a frictionless horizontal surface. They have masses mA and mB, respectively. When a horizontal force F is applied to crate A, the two crates move off to the right. (a) Draw clearly labeled free-body diagrams for crate A and for crate B. Indicate which pairs of forces, if any, are third-law action–reaction pairs.

A 1130-kg car is held in place by a light cable on a very smooth (frictionless) ramp (Fig. E5.8). The cable makes an angle of 31.0° above the surface of the ramp, and the ramp itself rises at 25.0° above the horizontal. (a) Draw a free-body diagram for the car.

Newton's First Law Exercises 17, 18, and 19 show two of the three forces acting on an object in equilibrium. Redraw the diagram, showing all three forces. Label the third force F3.