The gravitational force and potential energy at the surface of a planet with radius $r$ are $f_1$ and $u_1$, respectively. what are the gravitational force and gravitational potential energy, $f_2$ and $u_2$, respectively, at the surface of a planet with radius $2r$ that has the same mass density?

Aperson stands on a platform, initially at rest, that can rotate freely without friction. the moment of inertia of the person plus the platform is ip. the person holds a spinning bicycle wheel with its axis horizontal. the wheel has moment of inertia iw and angular velocity ωw. take the ωw direction counterclockwise when viewed from above. part a what will be the angular velocity ωp of the platform if the person moves the axis of the wheel so that it points vertically upward?

Photons with the highest energy have the longest period

Acar starts from rest at a stop sign and reaches a velocity of 25 m/s w in 4 seconds. determine the acceleration of the car. question 3 options: a) 6,25 m/s2 b)6.25 m/s c)100 m/s2 d)100 m/s