Exam 4: Newtons Laws: Explaining Motion

Consider two blocks, one made of wood and the other of lead. They have the same dimensions but the lead is much more massive. If they are dropped and fall long enough to reach terminal velocity, which block experiences a larger force from air resistance?

The force that accelerates a car on a level road is exerted by the

A car rounds a curve while maintaining constant speed. The correct statement is:

A ball hangs at rest from a string attached to the ceiling. The string pulls up on the ball with a force equal to its weight. The reaction to the upward force of the string on the ball is a ___________ (direction) force exerted by the __________ on the _______________.

An elevator is being lifted upward at a constant speed by a steel cable. All frictional forces are neglected. In this situation, forces on the elevator are such that

Your weight is 120 lb. Suppose you are standing on a scale in an elevator moving up with a constant speed of 4 m/s. What would be the reading on the scale?

A block of mass 2.5 kg is acted upon by a single force, producing an acceleration of 2.0 m/s². The force has a value of

A block, moving on a frictionless horizontal surface on Earth, requires a force if it is to be stopped. Now suppose that the same block, moving with the same speed on a frictionless horizontal surface on the Moon, where gravity is less, is to be stopped in the same time. We can say that, compared to the Earth,

Two blocks of different mass are connected by a string. The system is accelerated across a smooth horizontal surface by a force supplied by a rubber band connected to the less massive block. The tension in the connecting string will be

Newton's Law states that no force is required to keep a moving object in motion. Why, then, do you have to pedal continuously to ride a bicycle along a flat road? ____________________________ force

The force of the floor pushing up on you to counter your weight is an example of a ________ force.

A shiny, spherical, metal alien jumps out of a perfectly good airplane and skydives for a few seconds. Its photographic friend snaps photos of the sphere with a special camera that also captures the forces on the object. This diagram shows a few of the snapshots, but they are out of order. Place them in order, from the instant it jumps out of the plane and begins free-fall until the time it attains terminal velocity. Assume that the parachute has not deployed yet. If any of the diagrams depict a situation not physically possible, omit it from the ordering.

A light body sliding on a smooth horizontal surface collides with a heavy body. During the instant of contact the force exerted by the light body on the heavy body is ___________ (equal to, greater than, less than) the force exerted by the heavy body on the light body.

The force exerted on a body by moving air is proportional to the projected area of the body. Which falling body will have the larger terminal velocity, a flying squirrel with its wing membranes extended or a grey squirrel with the same mass?

An object is acted upon by the three forces shown above. In order to move the object upward,

A crate is acted upon by a net force of 100 N. An acceleration of 4.0 m/s² results. The weight of the crate is

A calculus book weighing 20 N rests on the floor of a classroom. The reaction to the force of the floor on the book is a force of

Refer to the set of snapshots Q, J, Y, and L. Which snapshot depicts the forces just after the parachute has fully opened?

The starship Enterprise locks onto an alien ship (whose mass is much greater than the Enterprise's mass) with its tractor beam (think of this as a futuristic rope) and starts to pull the alien ship toward it. Neither ship has its propulsion engines running. Which ship has greater acceleration towards the other?

A body of mass 1 kg is pushed across a horizontal table by a force of 1 N. The observed acceleration is 0.7 m/s²_. The force of friction opposing the motion is _______________ N.