Mechanics | Relativity Answers

A car with a mass of 2 895kg is standing still when it is hit by a car with a mass of 2269kg from behind after the collision car 1 notices that they move forward at a speed of 36km/h. Car 1 claims that car 2 must have been driving faster than 60km/h spped limit. Is the driver of car 1 correct? Prove by calculations

A 1500-kg blue convertible is travelling south, and a 2000-kg red sports utility vehicle is travelling west. If the momentum of the system consisting of the two cars is 8000kg•m/s directed at 60° west of south, what is the speed of each car?

A soccer ball of mass 0.420 kg is travelling with a speed of 4.50 ms at an angle of 20.0° counter clockwise from the +x-axis. What is the ball's x- and y-component of the momentum?

The net force acting to a 2.0-kg discuss while it is being thrown is (αt^2)i + (β+γt)j where α =25.0N/s^2, β = 30.0N and γ = 5.0N/s. If the discuss was originally at rest, what is the velocity after the net force has acted for 0.500 s? Express your answers in terms of the unit vectors i and j.
i- points in the positive x-axis direction
j- points in the positive y-axis direction

A 5-kg girl throws a 5.0-kg pumpkin at 10m.s to a 50-kg boy, who catches it. If both are on frictionless frozen lake, how fast does each of them move backward?

Jack and Jill are standing on the crate at rest on a frictionless horizontal surface of frozen pond. Jack has a mass of 75.0kg and Jill has a mass of 45.0kg and the crate has a mass of 15.0kg. They remember that they must fetch a pail of water so each umps horizontally from the top of the crate. Just after each jumps, that person is moving away from the crate with the speed of 4.0 m/s relative to the crate. What is the final speed of the crate if both Jack and Jill jump simultaneously and in the same direction? (Use the inertial reference system attached to the ground)

A mass 10kg is dropped from a height of 50cm.Find its
a)Potential Energy just before dropping.
b)Kinetic Energy just on touching the ground.
c)Velocity with which it hits the ground (given g=10ms-2)

Conservation of energy

A spring S of force constant k=100 N/m. is fixed to the base of a 30 degree incline.A mass m=50g. is held against the free end of the spring,so that the spring is compressed by 0.1 metre.If the mass is now released,calculate the distance travelled by the mass up the incline.don't ignore friction.
i tried using conservation of evergy theorem but i am not getting the solution.how should i start?

conservation of energy

a mass m is being lifted upward by means of a vertical spring of force constant k,with a uniform upward acceleration 'a'.If at the instant its velocity is v= A g.√(3m/k)
the upper end of the spring is suddenly brought to rest,calculate the max.extension in the spring.

An object uniformly accelerates from rest and reaches a velocity of 122.0 km/h north in 10.5 s. what was the average velocity of the object?