A 7.80-g bullet moving at 590 m/s penetrates a tree trunk to a depth of 5.60 cm. (a) Use work and energy considerations to find the average frictional force that stops the bullet.  N= (b) Assuming the frictional force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment it stops moving.  s=

A shopper weighs 2.00 kg of apples on a supermarket scale whose spring obeys Hooke's law and notes that the spring stretches a distance of 3.50 cm. (a) What will the spring's extension be if 6.00 kg of oranges are weighed instead? cm (b) What is the total amount of work that the shopper must do to stretch this spring a total distance of 6.50 cm beyond its relaxed position? J

2. Page 2 > of 7 F=40 30 In this problem, the block moves in the horizontal direction only. A. Find the work done if the force is applied for a distance of d = 2 m. B. If the mass is m= 6 kg and the initial velocity is V- 0. Use the work-energy theorem to find the final velocity C. If the process in part (B) took a time of t = 0.8s, use your answer from part (B) to Calculate the acceleration of the block. D. Now use Newton's second law ( in the x-direction) to calculate the acceleration. Your answers from Part ( C) and ( D) should be pretty close. They're different Because of rounding errors. dy

1. Some species of whales can dive to depths of 800m. What is the total pressure they experience at this depth? (The density of sea water = 1020 kg/m, and 1 ATM =10$ N/m) A 15.0-kg object is pulled along a horizontal surface at a constant speed by a 25 N force acting at 30° above the horizontal. How much work is done by this force as the object moves 10.0 m? A force of F = 3i + 0.5j – 5k), N is applied to a particle located at r = 2i +4k, m. Determine a) The torque vector; b) The angle between the vectors F and r 3. 4. A ball of mass Mi = 0.250 kg and velocity Voi = +5.00 m/s collides head-on with a ball of mass M2 = 0.800 kg initially at rest. No external forces act on the balls. If the collision is perfectly inelastic, find the velocity of mi after collision? Voi M1 M2 2.

What is the work needed to lift 15kg of water from a well 12 m deep ? ASSume the water has a constant upward acceleration of 0.7m/s²? 2

This is one question with two parts The force required to stretch a Hooke’s-law spring varies from 0N to 32.5N as we stretch the spring by moving one end 7.56 cm from its unstressed position. Find the force constant of the spring Answer in units of N/m Part two: find the work done in stretching the spring answer in units of J

A 268-kg crate is being pushed across a horizontal floor by a force P that makes an angle of 40.1 ° below the horizontal. The coefficient of kinetic friction is 0.248. What should be the magnitude of P, so that the net work done by it and the kinetic frictional force is zero? Number i eTextbook and Media Save for Later Units < 0 Attempts: 0 of 5 used Submit Answer

A sled plus passenger with total mass 59 kg is pulled 22 m across the snow (μk = 0.18) at a constant velocity by a force directed 25 degrees above the horizontal. a. Calculate the work of the applied force b. Calculate the work of friction c. Calculate the total work

A 7.80-g bullet moving at 520 m/s penetrates a tree trunk to a depth of 6.30 cm. Answer parts a-b.

A 20 kg box is resting on horizontal surface initially. Then a F = 50 N force pulls on the box by a cord at an angle of 20 degrees above horizontal. The kinetic frictional coefficient is 0.20. 1.What is the magnitude of acceleration of the box, a=? 2.What is the kinetic energy of the box after 3.0 seconds? (hint: calculate the velocity first v =?) 3.What is the work done by the force Fin 3.0 second? (hint: calculate the distance first, d = ?)