Questions from Modern Physics

Q: A 350-kg roller coaster car starts from rest at point

A 350-kg roller coaster car starts from rest at point A and slides down a frictionless loop-the-loop (Fig. P7.41). (a) How fast is this roller coaster car moving at point B? (b) How hard does it press...

Q: A car in an amusement park ride rolls without friction around a

A car in an amusement park ride rolls without friction around a track (Fig. P7.42). The car starts from rest at point A at a height h above the bottom of the loop. Treat the car as a particle. (a) Wha...

Q: A 2.0-kg piece of wood slides on a

A 2.0-kg piece of wood slides on a curved surface (Fig. P7.43). The sides of the surface are perfectly smooth, but the rough horizontal bottom is 30 m long and has a kinetic friction coefficient of 0....

Q: A 28-kg rock approaches the foot of a hill with

A 28-kg rock approaches the foot of a hill with a speed of 15 m/s. This hill slopes upward at a constant angle of 40.0° above the horizontal. The coefficients of static and kinetic friction between th...

Q: A 15.0-kg stone slides down a snow-

A 15.0-kg stone slides down a snow-covered hill (Fig. P7.45), leaving point A at a speed of 10.0 m/s. There is no friction on the hill between points A and B, but there is friction on the level groun...

Q: A 2.8-kg block slides over the smooth,

A 2.8-kg block slides over the smooth, icy hill shown in Fig. P7.46. The top of the hill is horizontal and 70 m higher than its base. What minimum speed must the block have at the base of the 70-m hil...

Q: A bungee cord is 30.0 m long and, when

A bungee cord is 30.0 m long and, when stretched a distance x, it exerts a restoring force of magnitude kx. Your father-in-law (mass 95.0 kg) stands on a platform 45.0 m above the ground, and one end...

Q: You are designing a delivery ramp for crates containing exercise equipment.

You are designing a delivery ramp for crates containing exercise equipment. The 1470-N crates will move at 1.8 m/s at the top of a ramp that slopes downward at 22.0°. The ramp exerts a 515-N kinetic f...

Q: An object moving in the xy-plane is acted on by

An object moving in the xy-plane is acted on by a conservative force described by the potential-energy function U(x, y)= a[(1/x2)+(1/y2)], where a is a positive constant. Derive an expression for the...

Q: The Great Sandini is a 60-kg circus performer who is

The Great Sandini is a 60-kg circus performer who is shot from a cannon (actually a spring gun). You don’t find many men of his caliber, so you help him design a new gun. This new gun has a very large...