A roller-coaster car has a mass of 1120 kg when fully loaded with passengers. As the car passes over the top of a circular hill of radius 21 m, its speed is not changing. (a) At the top of the hill, what is the normal force (using the negative sign for the downward direction) FN on the car from the track if the car's speed is v = 7.6 m/s? (b) What is EN if v = 19 m/s? Use g=9.81 m/s².

what is the answer ?!

A crate starts from rest and slides 8.05 m down a ramp. When it reaches the bottom it is traveling at a speed of 5.55 m/s. If the ramp makes an angle of 23.0o with the horizontal, what is the coefficient of friction between the crate and the ramp?

(a) A spaceship is projected vertically upward from the Earth's surface with an initial speed of 5.51 km/s, but unfortunately does not have a great enough speed to escape Earth's gravity. What maximum height does the spaceship reach (in m)? Ignore air resistance. 1.549e6 x Apply the conservation of mechanical energy, where v, = 0. You witt need to know the radius and mass of the Earth. Be careful with your signs when writing the potential energy expressions. Note that you can use energy conservation to write the initial potential energy of the system in terms of the escape velocity. Solve your equation for h. m initially at rest with (b) A meteorold falls from a height of 2.41 x 107 m above the surface of the Earth. What is the speed (in m/s) when the meteorite hits the Earth? Assume the meteoroid respect to the Earth. (Note that a meteorite is a meteorold that makes it to Earth's surface.) m/s