Exam 10: Interactions and Potential Energy

A 1.37-kg block is held in place against the spring by a 74-N horizontal external force (see the figure).The external force is removed,and the block is projected with a velocity v₁ = 1.2 m/s upon separation from the spring.The block descends a ramp and has a velocity at the bottom.The track is frictionless between points A and B.The block enters a rough section at B,extending to E.The coefficient of kinetic friction over this section is 0.24.The velocity of the block is at C.The block moves on to D,where it stops.The initial compression of the spring is closest to

A box of mass m is pressed against (but is not attached to)an ideal spring of force constant k and negligible mass,compressing the spring a distance x.After it is released,the box slides up a frictionless incline as shown in the figure and eventually stops.If we repeat this experiment but instead compress the spring a distance of 2x

A ball drops some distance and gains 30 J of kinetic energy.Do NOT ignore air resistance.How much gravitational potential energy did the ball lose?

In the figure,a stunt car driver negotiates the frictionless track shown in such a way that the car is barely in contact with the track at the top of the loop.The radius of the track is 9.9 m and the mass of the car is 1800 kg.Find the magnitude of the force of the car on the track when the car is at point A.You can treat the car as a point mass.

An 0.80-kg block is held in place against the spring by a 67-N horizontal external force (see the figure).The external force is removed,and the block is projected with a velocity v₁ = 1.2 m/s upon separation from the spring.The block descends a ramp and has a velocity v₂ = 1.9 m/s at the bottom.The track is frictionless between points A and B.The block enters a rough section at B,extending to E.The coefficient of kinetic friction over this section is 0.39.The velocity of the block is v₃ = 1.4 m/s at C.The block moves on to D,where it stops.The spring constant of the spring is closest to

The only force acting on an object moving along the x-axis is the conservative force given by F(x)= (2.00 N/m)x + (1.00 N/m³)x³. (a)What is the change in potential energy when the object moves from x = 1.00 m to x = 2.00 m? (b)What is the change in kinetic energy when the object moves from x = 1.00 m to x = 2.00 m?

A projectile is fired from ground level at an angle of 40.0° above horizontal at a speed of 30.0 m/s.What is the speed of the projectile when it has reached a height equal to 50.0% of its maximum height?

An 8.0-kg block is released from rest,with v₁ = 0.00 m/s,on a rough incline,as shown in the figure.The block moves a distance of 1.6-m down the incline,in a time interval of 0.80 s,and acquires a velocity of v₂ = 4.0 m/s.How much work does gravity do on the block during this process?

Which,if any,of the following statements concerning the work done by a conservative force is NOT true?

In the figure,a 4.0-kg ball is on the end of a 1.6-m rope that is fixed at 0.The ball is held at point A,with the rope horizontal,and is given an initial downward velocity.The ball moves through three quarters of a circle with no friction and arrives at B,with the rope barely under tension.The initial velocity of the ball,at point A,is closest to

The plot in the figure shows the potential energy of a particle,due to the force exerted on it by another particle,as a function of distance.At which of the three points labeled in the figure is the magnitude of the force on the particle greatest?

A 2.0 kg mass is moving along the x-axis.The potential energy curve as a function of position is shown in the figure.The kinetic energy of the object at the origin is 12 J.The system is conservative,and there is no friction. (a)What will be the kinetic energy at 2.0 m along the +x-axis? (b)What will be the speed of the object at 6.0 m along the +x-axis?

In the figure,a very small toy race car of mass m is released from rest on the loop-the-loop track.If it is released at a height 2R above the floor,how high is it above the floor when it leaves the track,neglecting friction?

When an object is solely under the influence of conservative forces,the sum of its kinetic and potential energies does not change.

When a particle is a distance r from the origin,its potential energy function is given by the equation U(r)= kr,where k is a constant and r = (a)What are the SI units of k? (b)Find a mathematical expression in terms of x,y,and z for the y component of the force on the particle. (c)If U = 3.00 J when the particle is 2.00 m from the origin,find the numerical value of the y component of the force on this particle when it is at the point (-1.00 m,2.00 m,3.00 m).

Is it possible for a system to have negative potential energy?

A ball drops some distance and loses 30 J of gravitational potential energy.Do NOT ignore air resistance.How much kinetic energy did the ball gain?

A mass is pressed against (but is not attached to)an ideal horizontal spring on a frictionless horizontal surface.After being released from rest,the mass acquires a maximum speed v and a maximum kinetic energy K.If instead the mass initially compresses the spring twice as far:

Two identical balls are thrown directly upward,ball A at speed v and ball B at speed 2v,and they feel no air resistance.Which statement about these balls is correct?

A very small 100-g object is attached to one end of a massless 10-cm rod that is pivoted without friction about the opposite end.The rod is held vertical,with the object at the top,and released,allowing the rod to swing.What is the speed of the object at the instant that the rod is horizontal?