Exam 7: Energy of a System

The only force acting on a 1.6-kg body as it moves along the x axis is given in the figure.If the velocity of the body at x = 2.0 m is 5.0 m/s,what is its kinetic energy at x = 5.0 m?

If = 5)0, = 8)0,and α = 30°,determine the scalar product of the two vectors shown.

The force an ideal spring exerts on an object is given by F_x = −kx,where x measures the displacement of the object from its equilibrium (x = 0)position.If k = 60 N/m,how much work is done by this force as the object moves from x = −0.20 m to x = 0?

A 4.0-kg block is lowered down a 37° incline a distance of 5.0 m from point A to point B.A horizontal force (F = 10 N)is applied to the block between A and B as shown in the figure.The kinetic energy of the block at A is 10 J and at B it is 20 J.How much work is done on the block by the force of friction between A and B?

If the resultant force acting on a 2.0-kg object is equal to N,what is the change in kinetic energy as the object moves from M to M?

A 3.0-kg block is dragged over a rough horizontal surface by a constant force of 16 N acting at an angle of 37° above the horizontal as shown.The speed of the block increases from 4.0 m/s to 6.0 m/s in a displacement of 5.0 m.What work was done by the friction force during this displacement?

In a contest,two tractors pull two identical blocks of stone the same distance over identical surfaces.However,block A is moving twice as fast as block B when it crosses the finish line.Which statement is correct?

Negative work can be done

Each of two vectors, And ,lies along a coordinate axis in the xy plane.Each vector has its tail at the origin,and the dot product of the two vectors is )Which possibility is correct?

The work Done by the force exerted by the spring on a mass attached to the end of the spring when the mass has displacement d Is

Positive work can be done

A 2.0-kg block slides down a frictionless incline from point A to point B.A force (magnitude P = 3.0 N)acts on the block between A and B,as shown.Points A and B are 2.0 m apart.If the kinetic energy of the block at A is 10 J,what is the kinetic energy of the block at B?

A block is pushed across a rough horizontal surface from point A to point B by a force (magnitude P = 5.4 N)as shown in the figure.The magnitude of the force of friction acting on the block between A and B is 1.2 N and points A and B are 0.5 m apart.If the kinetic energies of the block at A and B are 4.0 J and 5.6 J,respectively,how much work is done on the block by the force P between A and B?

When a crate of mass m is dragged a distance d along a surface with coefficient of kinetic friction μ_k,then dragged back along the same path to its original position,the work done by friction is

A particle is subject to the potential )What is the value of the y component of the force on the particle at the point (x,y)= (2.0,3.0)?

After a skydiver reaches terminal velocity,

A conservative force on a particle moving along the x axis is given by )Which of the following is a potential that is associated with this force?

A 2.0-kg body moving along the x axis has a velocity v_x = 5.0 m/s at x = 0.The only force acting on the object is given by F_x = (−4.0x)N,where x is in m.For what value of x will this object first come (momentarily)to rest?

The horizontal surface on which the block slides is frictionless.The speed of the block before it touches the spring is 6.0 m/s.How fast is the block moving at the instant the spring has been compressed 15 cm? k = 2.0 kN/m

Carts A and B have equal masses and travel equal distances on straight frictionless tracks while a constant force F is applied to A,and a constant force 2F is applied to B.The relative amounts of work done by the two forces are related by