Chapter 6: Dynamics I: Motion Along a Line

A$6.5cm$diameter ball has a terminal speed of$26m/s$. What is the ball’s mass?

A$2.0kg$object initially at rest at the origin is subjected to the time-varying force shown in the figure. What is the object’s velocity at$t=4s$?

A 5.0 Kg object initially at rest at the origin is subjected to the time-varying force shown below. What is the object’s velocity at $t=6sec.$?

The 1000 kg steel beam is supported by two ropes. What is the tension in each?

If you know all of the forces acting on a moving object, can you tell the direction the object is moving? If yes, explain how. If no, give an example.

A $20$kg loudspeaker is suspended $2.0$ m below the ceiling by two $3.0$-m-long cables that angle outward at equal angles. What is the tension in the cables?

Henry, whose mass is 95 kg, stands on a bathroom scale in an elevator. The scale reads 830 N for the first 3.0 s after the elevator starts moving, then 930 N for the next 3.0 s. What is the elevator’s velocity 6.0 s after starting?

An accident victim with a broken leg is being placed in traction. The patient wears a special boot with a pulley attached to the sole. The foot and boot together have a mass of 4.0 kg, and the doctor has decided to hang a 6.0 kg mass from the rope. The boot is held suspended by the ropes, as shown in FIGURE P6.41, and does not touch the bed.

a. Determine the amount of tension in the rope by using Newton’s laws to analyze the hanging mass.

b. The net traction force needs to pull straight out on the leg. What is the proper angle$\theta$for the upper rope?

c. What is the net traction force pulling on the leg?

An accident victim with a broken leg is being placed traction. The patient wears a special boot with a pulley attached to the sole. The foot and boot together have a mass of 4.0 kg and the doctor has decided to hang a 6.0 kg mass from the rope. The boot is held suspended by the ropes, as shown in FIGURE P6.41, and does not touch the bed a. Determine the amount of tension in the rope by using Newton’s laws to analyze the hanging mass. b. The net traction force needs to pull straight out on the leg. What is the proper angle u for the upper rope? c. What is the net traction force pulling on the leg? Hint: If the pulleys are frictionless, which we will assume, the tension in the rope is constant from one end to the other.

An accident victim with a broken leg is being placed in traction. The patient wears a special boot with a pulley attached to the sole. The foot and boot together have a mass of $4.0kg$, and the doctor has decided to hang a $6.0kg$mass from the rope. The boot is held suspended by the ropes, as shown in $FIGUREP6.41$, and does not touch the bed.

a. Determine the amount of tension in the rope by using Newton’s laws to analyze the hanging mass.

b. The net traction force needs to pull straight out on the leg. What is the proper angle u for the upper rope?

c. What is the net traction force pulling on the leg?