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Physics problems: dynamics

Part 2

 

 

Problem 11.

A box is sliding up an incline that makes an angle of 20 degrees with respect to the horizontal. The coefficient of kinetic friction between the box and the surface of the incline is 0.2. The initial speed of the box at the bottom of the incline is 2 m/s. How far does the box travel along the incline before coming to rest?

Solution

 

Problem 12.

A block weighing 80 N rests on a plane inclined at 30 degrees to the horizontal. The coefficients of static and kinetic friction are 0.2 and 0.1 respectively. What is the minimum magnitude of the force F, parallel to the plane, that will prevent the block from slipping?

Solution

 

Problem 13.

The tallest spot on Earth is Mt. Everest, which is 8857 m above sea level. If the radius of the Earth to sea level is 6369 km, how much does the magnitude of g change between sea level and the top of Mt. Everest?

Solution

 

Problem 14.

The value of g at the surface of the earth is 9.78 N/kg, and on the surface of Venus the magnitude of g is 8.6 N/kg. A cosmonaut has a mass of 60 kg on the surface of the earth. What will her weight be on the surface of Venus?

Solution

 

Problem 15.

A car (m=2000 kg) is parked on a road that rises 20 degrees above the horizontal. What are the magnitudes of (1) the normal force and (2) the static frictional force that the ground exerts on the tires?

Solution

 

 

 

Problem 16.

A rocket of mass kg is in flight. Its thrust is directed at an angle of 60 degrees above the horizontal and has a magnitude of . Find the magnitude and direction of the rockets acceleration. Give the direction as an angle above the horizontal.

Solution

 

Problem 17.

The speed of a bobsled is increasing because it has an acceleration of . At a given instant in time, the forces resisting the motion, including kinetic friction and air resistance, total 500 N. The mass of the bobsled and its riders is 300 kg.

(a) What is the magnitude of the force propelling the bobsled forward?

(b) What is the magnitude of the net force that acts on the bobsled?

Solution

 

Problem 18.

A person in a kayak starts paddling, and it accelerates from 0 to 0.8 miles/hour in a distance of 0.8 km. If the combined mass of the person and the kayak is 80 kg, what is the magnitude of the net force acting on the kayak?

Solution

 

Problem 19.

A dancer is standing on one leg on a drawbridge that is about to open. Before the drawbridge starts to open, it is perfectly level with the ground. The dancer is standing still on one leg. What is the x component (horizontal component) of the friction force?

Solution

 

Problem 20.

A block of mass 5 kg lies on a horizontal table. The block is at rest. The only forces acting on the block are the force due to gravity and the normal force from the table. What is the magnitude of the friction force?

Solution

 

 

 

 

 

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