Exam 6: Applications of Newtons Laws

A piano mover raises a 1000-N piano at a constant speed using a very light rope in a frictionless pulley system,as shown in the figure.With what force is the mover pulling down on the rope?

A 55-kg box rests on a horizontal surface.The coefficient of static friction between the box and the surface is 0.30.A horizontal 140-N force is applied to the box.What is the friction force on the box?

In the figure,block A has a mass of 3.00 kg.It rests on a smooth horizontal table and is connected by a very light horizontal string over an ideal pulley to block B,which has a mass of 2.00 kg.When block B is gently released from rest,how long does it take block B to travel 80.0 cm?

A highway curve of radius 100 m,banked at an angle of 45°,may be negotiated without friction at a speed of

A 3.0-kg brick rests on a perfectly smooth ramp inclined at 34° above the horizontal.The brick is kept from sliding down the plane by an ideal spring that is aligned with the surface and attached to a wall above the brick.The spring has a spring constant (force constant)of 120 N/m.By how much does the spring stretch with the brick attached?

A block of mass m sits at rest on a rough inclined ramp that makes an angle θ with the horizontal.What must be true about normal force F on the block due to the ramp?

Pulling out of a dive,the pilot of an airplane guides his plane into a vertical circle.At the bottom of the dive,the speed of the airplane is 320 m/s.What is the smallest radius allowable for the vertical circle if the pilot's apparent weight is not to exceed 7.0 times his true weight?

Two objects of unequal masses,M and m (M > m),are connected by a very light cord passing over an ideal pulley of negligible mass.When released,the system accelerates,and friction is negligible. Which one of the following free-body diagrams most realistically represents the forces acting on the two objects in the moving system?

Three boxes are pulled along a horizontal frictionless floor by a constant horizontal pull P.The boxes are connected by very light horizontal strings having tensions T₁ and T₂ as shown in the figure.Which of the following statements about the tensions is correct? (There could be more than one correct choice. )

The coefficients of static and kinetic friction between a 3.0-kg box and a horizontal desktop are 0.40 and 0.30,respectively.What is the force of friction on the box when a 15-N horizontal push is applied to the box?

Jason takes off across level water on his jet-powered skis.The combined mass of Jason and his skis is 75 kg (the mass of the fuel is negligible).The skis produce a forward thrust of 200 N and have a coefficient of kinetic friction with water of 0.10.Unfortunately,the skis run out of fuel after only 41 s.How far from his starting point has Jason traveled when he finally coasts to a stop?

One way that future space stations may create artificial gravity is by rotating the station.Consider a cylindrical space station 380 m in diameter that is rotating about its longitudinal axis.Astronauts walk on the inside surface of the space station.How long will it take for each rotation of the cylinder if it is to provide "normal" gravity for the astronauts?

A tightrope walker walks across a 30-m long wire tied between two poles.The center of the wire is displaced vertically downward by 1.0 m when he is halfway across.If the tension in both halves of the wire at this point is What is the mass of the tightrope walker? Neglect the mass of the wire.

When an object moves in uniform circular motion,the direction of its acceleration is

When a car goes around a circular curve on a horizontal road at constant speed,what force causes it to follow the circular path?

In order to simulate weightlessness for astronauts in training,they are flown in a vertical circle.If the passengers are to experience weightlessness,how fast should an airplane be moving at the top of a vertical circle with a radius of 2.5 km?

A car moving at a steady 10 m/s on a level highway encounters a bump that has a circular cross-section with a radius of 30 m.The car maintains its speed over the bump.What is the normal force exerted by the seat of the car on a 60.0-kg passenger when the car is at the top of the bump?

A 2.0-kg ball is moving with a constant speed of 5.0 m/s in a horizontal circle whose diameter is 1.0 m.What is the magnitude of the net force on the ball?

As shown in the figure,a woman is straining to lift a large crate,but without success because it is too heavy.We denote the forces on the crate as follows: P is the magnitude of the upward force being exerted on the crate by the person,C is the magnitude of the vertical contact force on the crate by the floor,and W is the weight of the crate.How are the magnitudes of these forces related while the person is trying unsuccessfully to lift the crate?

A 20-g bead is attached to a light 120-cm-long string as shown in the figure.This bead moves in a horizontal circle with a constant speed of 1.5 m/s.What is the tension in the string if the angle α is measured to be 25°?