Exam 5: Newtons Laws of Motion

Two masses, 5 kg and 3 kg, are connected by massless string. A cord is then attached to the 5-kg mass and the two masses are pulled across a smooth flat table. If the masses are moving at constant speed, what is the tension in the massless string (between the two masses)?

An 80-kg person falls out of an airplane and eventually reaches maximum speed (terminal velocity). We estimate the force of air friction at this speed to be

A 7-kg mass slides down a smooth incline. The incline makes an angle of 30° with the horizontal. The acceleration of the mass in the vertical direction is

A 7-kg mass slides down a smooth incline. The incline makes an angle of 30° with the horizontal. The acceleration of the mass along the incline is

A 3-m-long heavy chain, mass of 30 kg, is lowered from a barn loft by a farmer. The downward acceleration of the chain is 3 m/s $2$ . What is the tension in the chain at its midpoint of 1.5 m from an end?

A 5.0-kg mass hangs by a thin massless string from a tree branch. A strong breeze blowing in the horizontal direction imparts a force of 40 N on the mass. What is the angle of the string (relative to its initial vertical position)?

A person receives a 7-kg bag of groceries from the store clerk. The person then exerts an upward force of 28 N on the bag of groceries. The acceleration of the bag of groceries is

A 5.5-kg object, moving at constant velocity, is acted on by three forces. One force is 20 N along the +x axis. The second force is 25 N along the +y axis. What is the magnitude of the third force?

A net force of 147 N acts on a 15-kg mass. The acceleration of the mass is

A 500-N force is required to accelerate a car from rest to 3.9 m/s in 12 seconds. We estimate the mass of the car to be

A 4-kg mass and a 5-kg mass are in contact with each other while resting on a smooth table. A 20-N external force is applied to the 5-kg mass (in a direction toward the 4-kg mass). The contact force between the two masses is

The force that you exert on the Earth is

Two masses, 5 kg and 3 kg, are connected by massless string. A cord is then attached to the 5-kg mass, and the two masses are pulled across a smooth flat table. If the masses accelerate at 2 m/s $2$ , what is the tension in the massless string (between the two masses)?

A car initially traveling at 16 m/s undergoes braking and comes to a complete stop in two seconds. During the braking an 80-kg passenger, sitting on a smooth and flat seat, exerts how much force on the seat belt?

A 3-m-long heavy chain, mass of 30 kg, is held by one end from a barn loft by a farmer. The farmer then lets go of the chain. What is the tension in the chain at its midpoint (1.5 m from an end) as it is falling?

A 21-kg mass is pushed up a smooth incline using a horizontal force. The incline makes an angle of 35° with the horizontal, and the acceleration of the mass along the incline is 1.5 m/s $2$ . Find the horizontal force.

An 0.08-kg bullet is fired out of a gun at 250 m/s. The length of the barrel is 0.82 m; we estimate the recoil force of the gun to be

A 50-kg crate is pulled across a smooth floor using a rope. The crate is accelerating at 1 m/s $2$ and the rope makes an angle of 50° with the floor. The normal force is

The position of a $3.2 - \mathrm { kg }$ particle is given by $x ( t ) = b t ^ { 3 }$ , where $b = 6.5 \mathrm {~m} / \mathrm { s } ^ { 3 }$ . What is the force acting on the particle at time $t = 8$ seconds?

A steel cable is tightly tied (horizontally) to two trees that are 10 meters apart. A child hangs from the center of the cable, causing the center of the cable to be 2 cm below the original location (before the child grabbed the cable). The tension in the cable is 70,000 N. The mass of the child is