Mechanics | Relativity Answers

A parent spots their young child running towards the road at a constant speed of 0.81 m s−1.

The parent is 12.8 m behind the child and the child is 5.6 m from the road.

The parent accelerates at a steady rate towards the child and the child is running directly away from the parent.

If the parent catches the child just as they reach the road then at what rate must the parent have accelerated?

Two shuffleboard disks of equal mass, one orange and the other green, are involved in a perfectly elastic glancing collision. The green disk is initially at rest and is struck by the orange disk moving initially to the right at 5.00 m/s as in Figure P6.40a. After the collision, the orange disk moves in a direction that makes an angle of 37.0° with the horizontal axis while the green disk makes an angle of 53.0° with this axis as in Figure P6.40b. Determine the speed of each disk after the collision.

A railroad car of mass M moving at a speed v1 collides and couples with two coupled railroad cars, each of the same mass M and moving in the same direction at a speed v2. (a) What is the speed vf of the three coupled cars after the collision in terms of v1 and v2? (b) How much kinetic energy is lost in the collision? Answer in terms of M, v1, and v2.

A 65.0 - kg person throws a 0.045 0 - kg snowball forward with a ground speed of 30.0 m/s. A second person, with a mass of 60.0 kg, catches the snowball. Both people are on skates. The first person is initially moving forward with a speed of 2.50 m/s, and the second person is initially at rest. What are the velocities of the two people after the snowball is exchanged? Disregard friction between the skates and the ice.

A pitcher throws a 0.14-kg baseball toward the batter so that it crosses home plate horizontally and has a speed of 42 m/s just before it makes contact with the bat. The batter then hits the ball straight back at the pitcher with a speed of 48 m/s. Assume the ball travels along the same line leaving the bat as it followed before contacting the bat. (a) What is the magnitude of the impulse delivered by the bat to the baseball? (b) If the ball is in contact with the bat for 0.005 0 s, what is the magnitude of the average force exerted by the bat on the ball? (c) How does your answer to part (b) compare to the weight of the ball?

A ball is kicked such that it leaves the ground at an upwards angle with an initial velocity of vi.
The ball takes 3.1 s to hit the ground 26 m from where it was kicked.
What is the magnitude of the initial velocity of the ball? (in m s−1 to 2.s.f)
(note: ignore the effects of air resistance when solving this problem)

Obtain the directional derivative for a scalar field phi( X,Y,Z)= 3x^2y-y^3z^2 at the points (1,-2,-1) in the direction i+j+k

A cannon-ball is fired horizontally off of the edge of a cliff. When the cannon-ball hits the water below it hits the water with a velocity of 19 m s−1 at an angle of 65° below the horizontal.

How tall was the cliff? (in m to 2.s.f)

(note: ignore the effects of air resistance when solving this problem)

A 91-kg parent and a 21-kg child meet at the centre of an ice rink. They place their hands together and push. (a) Is the force experienced by the child more than, less than, or the same as the force experienced by the parent? (b) Is the acceleration ...
Is the acceleration of the child more than, less than, or the same as the acceleration of the parent?

A man walks 1km due east and then 1km due North his displacement