Other Physics Answers

A 0.60 𝑘𝑔 book slides on a horizontal table. The kinetic friction force on the book has magnitude 1.8 𝑁. (a) How much work is done on the book by friction during a displacement of 3.0 𝑚 to the left? (b) The book now slides 3.0 𝑚 to the right, returning to its starting point. During this second 3.0 𝑚 displacement, how much work is done on the book by friction? (c) What is the total work done on the book by friction during the complete round trip? (d) Based on your answer to part (c), would you say that the friction force is conservative or non-conservative? Explain. 

A small block with a mass of 0.0400 kg is moving in the 𝑥𝑦-plane. The net force on the block is described by the potential energy function 𝑈(𝑥) = (5.80 𝐽 𝑚2 ⁄ )𝑥 2 − (3.60 𝐽 𝑚3 ⁄ )𝑦 3 . What are the magnitude and direction of the acceleration of the block when it is at the point (𝑥 = 0.300𝑚, 𝑦 = 0.600𝑚)? 

The potential energy of a pair of hydrogen atoms separated by a large distance 𝑥 is given by 𝑈(𝑥) = −𝐶6/𝑥 6 , where 𝐶6 is a positive constant. What is the force that one atom exerts on the other? Is this force attractive or repulsive?

A ball is thrown upward with an initial velocity of 15 m/s at an angle of 60.0° above the horizontal. Use energy conservation to find the ball’s greatest height above the ground.

A force parallel to the 𝑥-axis acts on a particle moving along the 𝑥-axis. This force produces potential energy 𝑈(𝑥) given by 𝑈(𝑥) = 𝛼𝑥 4 , where 𝛼 = 0.630 J/m4 . What is the force (magnitude and direction) when the particle is at 𝑥 = −0.800 m?

A bullet with a mass of 5.00 𝑔𝑟𝑎𝑚𝑠 and a speed of 600 𝑚/𝑠 penetrates a tree to a depth of 4.00 cm. Find the average friction force that stops the bullet. Assuming that the frictional force is constant, determine how much time elapsed between the moment the bullet entered the tree and the moment it stopped.

A body weighing 64𝑙𝑏 slides down from rest at the top of a plane 18𝑓𝑡 long and inclined 30𝑜 above the horizontal. The coefficient of friction is 0.10. Find the velocity of the body as it reaches the bottom of the plane.

Spring is compressed to a length of 20 cm by a 20 kg object on a 20 degrees inclined surface with coefficient of kinetic friction 0.30. What is the initial velocity of the object moving up the plane? The spring constant is 980 N/m

You are at the grocery store check-out buying a 6-pack of your favorite beverage. You grab the handle of the 6-pack and drag it along the level counter at a constant velocity by pulling up and over with a force of 35 N at an angle of 20° above the horizontal. The coefficient of friction between the counter and the 6-pack carton is 0.35. Find the mass of the 6-pack.

Vector A has magnitude 4.0 units and vector B has magnitude 5.0 units. The angle between A and B is 60.0°. What is the magnitude of A+B ?