A 12.0 kg mass is dropped from a hot air balloon at a height of 345 m above the ground. Find it's speed at points 250 m above the ground.

A 43-kg pole vaulter running at 10 m/s vaults over the bar. Her speed when she is above the bar is 1.5 m/s. Neglect air resistance, as well as any energy absorbed by the pole, and determine her altitude as she crosses the bar.

A spring-loaded toy gun is used to launch a 10 g plastic ball.  The spring, which has a spring constant of 10N/m is compressed by 10 cm as the ball is pushed into the barrel.  When the trigger is pulled, the spring is released and shoots the ball back out horizontally.  a) What is the ball's speed as it leaves the barrel?  Assume the friction is negligible. b) If the toy gun was shot vertically upward, how high would the ball go?  Use energy concepts.

A 59-kg pole vaulter running at 10 m/s vaults over the bar. Her speed when she is above the bar is 1.3 m/s. Neglect air resistance, as well as any energy absorbed by the pole, and determine her altitude as she crosses the bar.

a girl and her bicycle have a total mass of 60kg. at the top of the hill her speed is 5.0m/s. The hill is 5.0 m high and 100 m long. If the force of friction as she rides down the hill is 20N, what is her speed at the bottom?

.  An electron in a television tube is accelerated uniformly from rest to a speed of 8.4×107m/s over a distance of 2.5 cm. What is the power delivered to the electron at the instant that its displacement is 1.0 cm?

The figure here shows a plot of potential energy U versus position x of a 0.888 kg particle that can travel only along an x axis. (Nonconservative forces are not involved.) Three values are Ug = 15.0 J, Ug = 35.0 J and Uc = 45.0 J. The particle is released at x = 4.50 m with an initial speed of 7.04 m/s, headed in the negative x direction. (a) If the particle can reach x = 1.00 m, what is its speed there, and if it cannot, what is its turning point? What are the (b) magnitude and (c) direction of the force on the particle as it begins to move to the left of x = 4.00 m? Suppose, instead, the particle is headed in the positive x direction when it is released at x = 4.50 m at speed 7.04 m/s. (d) If the particle can reach x = 7.00 m, what is its speed there, and if it cannot, what is its turning point? What are the (e) magnitude and (f) direction of the force on the particle as it begins to move to the right of x = 5.00 m? Uc UB UA 4 6 x (m) (a) Number Unit (b) Number Unit (c) (d) Number…

A bucket of water of mass 20 kg is pulled at constant velocity up to a platform 45 meters above the ground. This takes 18 minutes, during which time 8 kg of water drips out at a steady rate through a hole in the bottom. Find the work needed to raise the bucket to the platform. (Use g=9.8m/s^2) (include units)

Given: A shooting guard throws a basketball m = 1 kg straight up with an initial speed of v0 = 5.5 m/s. He releases the ball at shoulder height h0 = 1.95 m. Let gravitational potential energy be zero at ground level. Give the total mechanical energy of the ball E in terms of maximum height hm it reaches, the mass m, and the gravitational acceleration g.  What is the height, hm in meters?

How much work is done against gravity to move an 800 kg weather monitor 300 km into the air? (re = 6.38 × 10® m, Me = 5.98 × 1024