A single force F(x) = −8.0x (in newtons) acts on a 3.0-kg body. When x = 6.75 m, the speed ofthe body is 4.0 m/s. What is its speed at x = 2.5 m?

Superman wanted to launch a small rocket using a spring mounted vertically on the ground. He placed the 4.0 kg rocket on a very stiff spring. The spring is 1.5m long, it has negligible mass and a spring force constant of 100,000 N/m. He compresses the spring for 1.1m. He then releases the spring. If y = 0 at the ground level, the system consists of the rocket and the spring; (I) what is the energy of the system before Superman releases the rocket? (II)What is the maximum height the rocket can reach if we can neglect air resistance? (III) If air resistance can’t be neglected, it exerts a constant force of 37.5N on the rocket, how high will the rocket reach? (IV) What is the speed of the rocket when it is 120.0 m from the ground if air resistance is taken into account?

(11) Block 1 has a mass of 4.95 kg and block 2 has a mass of 5.58 kg. Block 2 is released from rest at a height of h = 1.00 m above the floor. 2 h (a) Find the speed of the 5.58 kg block just before it hits the floor, if there is no friction. Submit Answer Tries 0/10 (b) Find the speed of the 5.58 kg block just before it hits the floor if the coefficient of kinetic friction of the 4.95 kg block is 0.483.

Consider a 0.5 kg mass at the top of a 1.5 m high (vertical) incline. if it is allowed to slide down with negligible friction, what will be its speed (in m/s) at the bottom?

An object of mass 10 kg is released at point A, slides to the bottom of a 30° inclination and then collides with a horizontal massless spring, compressing it to a maximum distance of 0.75 m (See picture). The spring constant is 500 M/m, the height of the inclination is 2.0 m, and the horizontal surface is frictionless. (a) What is the velocity of the object at the bottom of the slope? (b) What is the frictional work on the object while on the slope? (c) The spring recoils and sends the object down the slope. What is the velocity of the object when it reaches the bottom of the slope? (d) What is the vertical distance back up the slope?

During world war 2, a military parachutist fell 0.37km from an airplane without being able to open his chute, but luckily was able to land in snow, suffering only with minor injuries. Assume that his speed at impact was 56m/s, and his mass, including his gear was 85kg, and that the magnitude of force on him from the snow was at the survivable limit of 1.2 x 10^5 N. What is the magnitude of the impulse on him from the snow? (Answer in one decimal place, no unit) sample answer: 1.1 x 10^3 (enter the 1.1 only)

A particular spring has a rest length of 5.0 cm when it is not compressed, and a length of 4.5 cm when a mass of 10kg is placed on top of it in the lab. How long is the spring with the 10kg mass on top when it is taken into an elevator accelerating upwards at 1.0 m/s2? Please answer in units of centimeters.

A 75-kg meteorite buries itself 5.0m into soft mud. The force between the meteorite and the mud is given by F{x) = (640N/m3)x3, where x is the depth in the mud. What was the speed of the meteorite when it initially impacted the mud?

please answer iii)