Exam 6: Conservation of Energy

A 1.1 kg seagull takes off from a piling along the California coast and accelerates in 0.50 s to a flight speed of 7.5 m/s. Assuming the seagull flies along a horizontal path (at the same height as its takeoff), what average power is delivered by the bird's wings during the takeoff?

A 20.0 kg box slides up a 12.0 m long incline at an angle of 30.0 degrees with the horizontal. A force of 150 N is applied to the box to pull it up the incline. The applied force makes an angle of 10.0 degrees to the incline. What is the work done by the applied force?

A 30.00 kg box slides up a 12.00 meter long incline at an angle of 30.00 degrees above the horizontal. Friction is negligible. The change in gravitational potential energy is

As a hiker descends a hill, the work done by gravity on the hiker is

A dragster drives a quarter mile (402 m) at a constant rate of acceleration, starting from rest and finishing the race with a final speed of 450 km/hr. The mass of the dragster, together with its driver, is 975 kg. What average power is provided by the engine, if 50% of the power output is delivered to the wheels? Neglect dissipative forces.

A 5.00 kg box slides up a 10.0 m long incline at an angle of 20.0 degrees with the horizontal, pushed by a 40.0 N force parallel to the incline. The coefficient of kinetic friction is 0.100. The change in kinetic energy is

An asteroid of mass 1.4 × 10¹⁴ kg is observed to have an escape speed equal to a typical person's maximum jumping speed, 3.0 m/s. What is its radius?

A spring is stretched from 0.500 m to 0.800 m. Assume the unstretched position is 0.00 m. If the spring constant of the spring is 10.0 N/m, what is the work done on the spring?

The graph shows the force on an object as it moves a distance x. What is the work done by the force as the object moves from 0.0 m to 6.0 m?

A spring-powered launcher has a spring with a constant of 150 N/cm. The launcher is prepared by compressing the spring by 5.00 cm. If the mass of the projectile is 5.00 grams, what is the speed of the projectile when it is launched?

A 1.1 kg seagull takes off from a piling along the California coast and accelerates in 0.50 s to a flight speed of 7.5 m/s. The seagull flies along a slightly inclined path, such that at the end of the 0.50 s period, it is 5.3 m above its point of takeoff. What average power is delivered by the bird's wings during the takeoff?

A 120 N force is applied at an angle of 30.0 degrees above the horizontal to a 4.00 kg box on a frictionless surface. The box moves a horizontal distance of 8.00 meters. The change in the kinetic energy of the box is

A 5.00 gram bullet has a velocity of 300 m/s. It strikes a block of wood and penetrates to a depth of 10.0 cm. The average force of the block of wood on the bullet is

A spring with a spring constant of 8.0 N/m is initially compressed to 5.0 cm. The work done (by the external force) as it is compressed another 15 cm, to a total compression of 20 cm, is

A 2.00 kg pendulum bob on a string 1.50 m long, is released with a velocity of 4.00 m/s when the support string makes an angle of 30.0 degrees with the vertical. What is the angle with the vertical the bob makes at the highest point of its motion?

A 1800 kg car moving at 20 m/s hits an initially uncompressed spring with a spring constant of 2.0 × 10⁶ N/m. The maximum compression of the spring is

A 75 kg road bicycle racer rides down the highway from Pikes peak. During one stretch of the ride, he descends 5 meters in 12.5 seconds, while accelerating from 35 km/hr to 55 km/hr. Assuming rotational kinetic energy and dissipative forces to be negligible, what average power is supplied by the gravitational force during this time?

A student lifts a weight of 10.0 N a distance of 0.500 meters. The energy needed to do this work in calories is (1 cal = 4.186 Joules)

A student lifts a weight of 10.0 N a distance of 0.5 meters. If this exercise is repeated 50 times in 100 seconds, then the average power output of the student is

The explosion in a cannon exerts an average force of 30,000 N for L meters, the length of the cannon. What length of the cannon would be necessary to shoot a 2.0 kg projectile from the surface of the Earth to a distance of 6.84 × 10⁸ m from the center of the Earth (the same as the distance to the Moon)? (G = 6.67 × 10⁻¹¹ N·m²/kg², ME = 5.97 × 10²⁴ kg, and RE = 6.37 × 10⁶ m.)