Forces (DP IB Physics: HL)

A wooden block of weight W rests on a rough board that produces a friction force F. The end of the board is then raised up to angle θ until the block slides down the plane of the board at constant velocity v.

Which row describes the forces acting on the block as it slides down the board?

Which row gives the correct Newton’s third law force pair for a book on a table?

An object of mass m is connected via a frictionless pulley to an object of mass M, where M > m. M rests on a horizontal rough surface with a frictional force f.

What is the acceleration of the system?

A photo hangs from two strings. It has a weight W and the two strings have equal tension T.

What is the free–body diagram for this situation?

Which of the following are possible values for the maximum coefficient of static friction,  and dynamic friction, ?

A.	0.012	0.78
B.	0.35	0.12
C.	1.50	0.90
D.	0.26	–0.77

A uniform ladder resting in equilibrium on rough ground leans against a smooth wall.

Which diagram correctly shows the forces acting on the ladder?

A block of mass m rests on a trolley of mass M. The coefficient of dynamic friction between the block and the trolley is µ.

A horizontal force F acts on the block causing it to slide over the trolley. What is the acceleration of the trolley?

A sled with a child has a combined weight of 400 N and rests on a horizontal surface. The coefficient of static friction between the sled and the surface is 0.50 and the coefficient of dynamic friction is 0.30.

A horizontal force F is applied to the sled and its magnitude increases uniformly from zero. Once the sled starts moving, the pulling force no longer increases.

What is the minimum resultant force required on the moving sled?

Two coplanar forces of 11 N and 7 N act on an object. Which force could not be the resultant for these two forces?

Two boxes in contact are pushed in a line along a floor with a force F. The boxes are moving at a constant speed. Box X has a mass m and box Y has a mass 3m.

What is the resultant force acting on Y?

A frictionless spring-operated latched is fitted to a door. 

When the latch is pushed in, the spring compresses.

When the latch is released, which of the following best represents how acceleration a of the latch varies with the distance x it moves before stopping? 

Elaborate chandeliers can be modelled as layers of hanging bars. The diagram shows one such model with a mass m suspended from two bars of negligible mass, connected by five light strings. Each layer has N number of strings. 

Which expression gives the tension in any single string? 

Two blocks, one made of wood and the other of iron, are arranged at rest on the ground. 

Which of the following statements is correct? 

A child of mass m sits in a car seat which is accelerating horizontally at 0.2g, where g is the acceleration due to gravity. 

What is the magnitude of the total force exerted by the car seat on the child? 

The following scenarios describe specific types of motion: 

1. A diver equipped so that they remain at constant depth below the water surface without any effort on their part
2. An athlete clearing the bar in a high jump
3. A parachutist descending at terminal velocity with the parachute fully open

In which of the scenarios does the person concerned experience 'weightlessness'? 

A pendulum bob hangs from the ceiling in a carriage in a train and is just above a certain mark on the floor when the train is at rest. When the train is moving with a constant velocity forward, which statement best outlines the position of the bob? 

Two masses m and nm, where n > 1, are joined by a light string which passes over a frictionless pulley. The acceleration of free fall is g. 

What is the acceleration of the masses a and the tension in the string T? 

Two bodies, X and Y, having masses m_X and m_Y respectively, exert forces on each other and have no external forces acting on them. The force acting on X is F, which gives X an acceleration a_X.

What is the magnitude of the force on Y and its acceleration?

Two blocks with mass 5m and 3m are pushed along a smooth horizontal surface by an applied force F.

What is the magnitude of the force exerted between the blocks? 

Forces act in a variety of situations described below: 

1. The centripetal force holding a satellite in orbit round the Earth and the weight of the satellite 
2. Repulsive forces experienced by anti-parallel current-carrying conductors 
3. Attractive forces between two gas molecules passing close to each other
4. Attractive forces between the nucleus and orbiting electrons in an atom

Which of the situations describe pairs of forces as required by Newton's third law?