Mechanics | Relativity Answers

A body moves a distance of s=2t^3-4t+5 in t seconds.
a) what is the velocity of the body after 3 seconds ?
b)what is the acceleration after 4 seconds ?
c)what is the time when the velocity is zero?
d)what is the time when the acceleration is zero?

A ball with mass m move with speed v as it collides with a stationary ball with mass 2m. After the collision the first ball bounces off in the opposite direction at v/sqrt(2) of its initial speed.Find the velocity of the second ball (mass 2m) immediately after the collision.

A torque of 2 N.m increases a wheel's angular speed by 3 times in 4.0 s. The rotational inertia of the wheel is 0.04 kg.m^2. The initial angular speed of the wheel is

A 100-g block is initially moving to the right on a horizontal surface at a speed of 2.0 m/s. Shortly, the block compresses a horizontal spring of k = 70 N/m. If 120 mJ of the mechanical energy is dissipated by friction, the maximum compression of the spring is

A 1.3-ton sedan car travellng west at 72 km/h runs into a 2.5-ton SUV travelling south at 36 km/h at an intersection. Given that the cars stick together after the collision, their speed and the direction are:

The radius R of collapsing spinning star drops to 1/3 its initial value wheres the mass M remains unchanged. The star spins as a rigid body and its rotational inertia I =2/5 MR^2. The ratio of the new rotational kinetic energy to the initial rotational kinetic energy is

In figure blocks of mass m1=3kg and m2=4kg are connected by a string of negligible mass and are initially held in a place. The heavier block is tilted at 30 degrees. The coefficient of kinetic friction between the block of mass 3kg and the horizontal surface is 0.3. The coefficient of kinetic friction bock mass 4kg and the inclined surface is 0.1. The pulley has a negligible mass and the friction. once they are released, the blocks move, what then is the tension in the string and accelaration?

Bill has set his GPS to track his route. At the conclusion of his hike, the receiver indicates that he walked 3.5 miles north, 1.0 miles northeast, 1.5 miles south. How far away is Bill from his original position

a bullet is fired horizontally above a tunnel 6m high and strikes a target 100m away. Find the time if flight. (g=10ms-2)

A boat with a total mass of 500kg is traveling north on a lake. The motor of the provides a force of 400N in the northerly direction. The wind blows 30 degrees away from the northerly direction slightly towards east. it exerts a force of 300N on the boat. Find the acceleration of the boat including magnitude and direction. Assume friction between the boat and the water of the lake is negligible