Exam 6: Energy of a System

The only force acting on a 2.0-kg body moving along the x axis is given by F_x = (2.0x)N,where x is in m.If the velocity of the object at x = 0 is +3.0 m/s,how fast is it moving at x = 2.0 m?

A 2.0-kg block situated on a frictionless incline is connected to a light spring (k = 100 N/m),as shown.The block is released from rest when the spring is unstretched.The pulley is frictionless and has negligible mass.What is the speed of the block when it has moved 0.20 m down the plane?

An object moving along the x axis is acted upon by a force F_x that varies with position as shown.How much work is done by this force as the object moves from x = 2 m to x = 8 m?

For a force to be a conservative force,when applied to a single test body

The only force acting on a 2.0-kg body as it moves along the x axis is given by F_x = (12 -2.0x)N,where x is in m.The velocity of the body at x = 2.0 m is 5.5 î m/s.What is the maximum kinetic energy attained by the body while moving in the +x direction?

A 4.0-kg block is lowered down a 37 $\degree$ 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?

Which of the following is a conservative force? (All refer to a car on a slope. )

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?

Two cannonballs are dropped from a second floor physics lab at height h above the ground.Ball B has four times the mass of ball A.When the balls pass the bottom of a first floor window at height $\frac { h } { 4 }$ above the ground,the relation between their kinetic energies,K_A and K_B,is

A constant force of 12 N in the positive x direction acts on a 4.0-kg object as it moves from the origin to the point $( 6 \tilde { \mathbf { i } } - 8 \tilde { \mathbf { j } } )$ m.How much work is done by the given force during this displacement?

If $| \overrightarrow { \mathbf { A } } |$ = 6.0, $| \overrightarrow { \mathbf { B } } |$ = 5.0,and $\alpha$ = 40 $\degree$ ,determine the scalar product of the two vectors shown.

A 12-kg block on a horizontal frictionless surface is attached to a light spring (force constant = 0.80 kN/m).The block is initially at rest at its equilibrium position when a force (magnitude P = 80 N)acting parallel to the surface is applied to the block,as shown.What is the speed of the block when it is 13 cm from its equilibrium position?

If the vectors $\overrightarrow { \mathrm { A } }$ and $\vec { B }$ have magnitudes of 10 and 11,respectively,and the scalar product of these two vectors is -100,what is the magnitude of the sum of these two vectors?

A mass attached to the end of a spring is pulled out and released on a surface with friction.The work $\overrightarrow { \mathbf { F } } _ { sp } \cdot d~ \overrightarrow { \mathbf { x } }$ done on the mass by the force exerted by the spring

Sally,who weighs 450 N,stands on a skate board while Roger pushes it forward 13.0 m at constant velocity on a level straight street.He applies a constant 100 N force.

A particle is subject to the potential $U = 2 x ^ { 2 } y + 6 y$ .What is the value of the y component of the force on the particle at the point (x,y)= (2.0,3.0)?

Each of two vectors, $\overrightarrow { \mathrm { D } } _ { 1 }$ and $\overrightarrow { \mathrm { D } } _ { 2 }$ ,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 $\overrightarrow { \mathrm { D } } _ { 1 } \cdot \overrightarrow { \mathrm { D } } _ { 2 } = - \left| \overrightarrow { \mathrm { D } } _ { 1 } \right| \left| \overrightarrow { \mathrm { D } } _ { 2 } \right|$ .Which possibility is correct?

A 2.0-kg block sliding on a frictionless horizontal surface is attached to one end of a horizontal spring (k = 600 N/m)which has its other end fixed.The speed of the block when the spring is extended 20 cm is equal to 3.0 m/s.What is the maximum speed of this block as it oscillates?

A block slides on a rough horizontal surface from point A to point B.A force (magnitude P = 2.0 N)acts on the block between A and B,as shown.Points A and B are 1.5 m apart.If the kinetic energies of the block at A and B are 5.0 J and 4.0 J,respectively,how much work is done on the block by the force of friction as the block moves from A to B?

Planets go around the sun in elliptical orbits.The highly exaggerated diagram below shows a portion of such an orbit and the force on the planet at one position along that orbit.The planet is moving to the right.F_|| and $\mathrm { F } _ { \perp }$ are the components of the force parallel (tangential)and perpendicular (normal)to the orbit.The work they do is W_|| and $W _ { \perp }$ .At the position shown