A projectile must have 150 kJ of kinetic energy to break through a city wall. Which of the following projectiles will break through the wall?
A. Mass = 100 kg; speed = 55 m/s
B. Mass = 150 kg; speed = 42 m/s
C. Mass = 200 kg; speed = 36 m/s
D. All of the above

The dot diagram represents the motion of the motorcycle as it moves from left to right

Most short-period comets do not have randomly oriented orbits because

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 740 n/m. it is initially at rest on an inclined plane that is at an angle of theta= 26 with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is uk = 0.17. in the initial position, where the spring is compressed by a distance of d = 0.16 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. the block's initial mechanical energy is 9.472 j.b. if the spring pushes the block up the incline, what distance l in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.