Classical Mechanics Answers

You are sitting in a plane, in straight horizontal flight at constant speed of 250 \text{m.s}^{-1}

m.s−1

, when you drop your pen from height 0.30 m above your leg. You've just shown that it hits your leg after 0.25 s.

How far does the plane travel in that time?

A block is pulled to the right with a force of 250 N forming an angle of 42º, applying this force, the block reaches an acceleration of 1.5m / s.

The coefficient of friction is 0.3

a) Calculate the mass of the block.

b) Determine the normal force and the friction force

A 1.6 kg cat X at 1.2 m apart from the axis of rotation through point O on the platform that rotates horizontally (anti-clockwise) without friction. The platform has moment of inertia 80.0 kgm^2 and radius 2.0 m. The platform initially at rest, starts to rotate under a tangential force F of constant magnitude 25.0 N. Calculate the

(a) moment of inertia for the whole rotating system.

(b) angular acceleration of the system.

(c) angular speed of the system after 9.0 s.

(d) angular momentum of the system after 9.0 s.

A 750 N athlete is doing a push-up exercise by putting his palms and toes on the floor. The athlete’s center of mass is 15 cm from his palms. The horizontal distance between his toes and palms is 120 cm. Assume the posture of the athlete as a rigid body,

(a) sketch a free body diagram of the athlete.

(b) calculate the force acting on each of his palms.

A flywheel of moment inertia 95 kgm^2 rotates about its axis with an angular velocity 60 rad/s. Coaxial with the flywheel is a gear-wheel of moment inertia 5.0 kgm^2, initially stationary. The two wheels are then joined together.

Calculate the angular velocity of both wheels together after they have been joined.

A flywheel of moment inertia 95 kg m2 rotates about its axis with an angular velocity 60 rad/s. Coaxial with the flywheel is a gear-wheel of moment inertia 5.0 kgm2, initially stationary. The two wheels are then joined together.

Calculate the angular velocity of both wheels together after they have been joined.

A 5.00-kg box slides 3.00 m across the floor before coming to rest. What is the coefficient of kinetic friction between the floor and the box if the box had an initial speed of 3.00 m/s?

Describe the type of spring "constant" needed to produce a constant restoring force like curve (a) in fig. 7-1.