6. Intro to Forces (Dynamics)

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?

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.

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.

Exercises 23, 24, 25, 26, and 27 describe a situation. For each, identify all forces acting on the object and draw a free-body diagram of the object. An ice hockey puck glides across frictionless ice.

Exercises 23, 24, 25, 26, and 27 describe a situation. For each, identify all forces acting on the object and draw a free-body diagram of the object. Your physics textbook is sliding across the table.

A baseball player is sliding into second base. Identify the forces on the baseball player.

A rubber ball bounces. We'd like to understand how the ball bounces. c. Draw a free-body diagram of the ball during its contact with the ground. Is there a net force acting on the ball? If so, in which direction?

A chandelier hangs from a chain in the middle of a dining room. Identify the forces on the chandelier.

If a car stops suddenly, you feel 'thrown forward.' We'd like to understand what happens to the passengers as a car stops. Imagine yourself sitting on a very slippery bench inside a car. This bench has no friction, no seat back, and there's nothing for you to hold onto. b. Draw your free-body diagram. Is there a net force on you? If so, in which direction?

A jet plane is speeding down the runway during takeoff. Air resistance is not negligible. Identify the forces on the jet.

Problems 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, and 52 describe a situation. For each, draw a motion diagram, a force-identification diagram, and a free-body diagram. A Styrofoam ball has just been shot straight up. Air resistance is not negligible.

Problems 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, and 52 describe a situation. For each, draw a motion diagram, a force-identification diagram, and a free-body diagram. A rocket is being launched straight up. Air resistance is not negligible.

Problems 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, and 52 describe a situation. For each, draw a motion diagram, a force-identification diagram, and a free-body diagram. A model rocket is fired straight down from the top of a tower.

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.

A heavy steel cable attached to a motor is lifting a girder. The girder is speeding up.(a) Draw an interaction diagram

A tennis racket swung over the server's head hits a tennis ball horizontally. (c) Draw a free-body diagram for each object in the system. Use dashed lines to connect members of an action/reaction pair.

A weightlifter stands up at constant speed from a squatting position while holding a heavy barbell across his shoulders. (b) Identify the "systemm" on your interaction diagram

Block A in FIGURE EX7.4 is sliding down the incline. The rope is massless, and the massless pulley turns on frictionless bearings, but the surface is not frictionless. The rope and the pulley are among the interacting objects, but you'll have to decide if they're part of the system. (a) Draw an interaction diagram

Block A in FIGURE EX7.4 is sliding down the incline. The rope is massless, and the massless pulley turns on frictionless bearings, but the surface is not frictionless. The rope and the pulley are among the interacting objects, but you'll have to decide if they're part of the system. (c) Draw a free-body diagram for each object in the system. Use dashed lines to connect members of an action/reaction pair.