Question

Kinematic homework 1
1. Georgia is jogging with a velocity of 4 m/s when she accelerates at 2 m/s/s for 3 seconds. How fast is Georgia running now?
2. In a football game, running back is at the 10 yard line and running up the field towards the 50 yard line, and runs for 3 seconds at 8 yd/s. What is his current position (in yards)?
3. A cat is moving at 18 m/s when it accelerates at 4 m/s/s for 2 seconds. What is his new velocity?
4. A race car is traveling at +76 m/s when is slows down at -9 m/s/s for 4 seconds. What is his new velocity?
5. An alien spaceship is 500 m above the ground and moving at a constant velocity of 150 m/s upwards. How high above the ground is the ship after 5 seconds?
6. A bicyclist is traveling at +25 m/s when he begins to decelerate at -4 m/s/s. How fast is he traveling after 5 seconds?
7. A squirrel is 5.0 m away from you while moving at a constant velocity of 3 m/s away from you. How far away is the squirrel after 5 seconds?
8. A ball is dropped off a very tall canyon ledge. Gravity accelerates the ball at 9.8 m/s/s. How fast is the ball traveling after 5 seconds?
9. During a race, a dragster is 200 m from the finish line when something goes wrong and it stops accelerating. It travels at a constant velocity of 45 m/s for 3 seconds to try to finish the race. How far from the finish line is the dragster after 3 seconds?
10. A dog is 60 m away while moving at a constant velocity of 10 m/s towards you. Where is the dog after 4 seconds?
11. Isaac throws an apple straight up (in the positive direction) from 1.0 m above the ground, reaching a maximum height of 35 meters. Neglecting air resistance, what is the ball’s velocity when it hits the ground?
12. Two kittens are on opposite sides of a field, 250 m apart. Kitten A runs at a constant speed of 25 m/s due east on a collision course with kitten B, which is traveling west at 12 m/s. How much time elapses before the two kittens collide?

Answer 1

12) You can answer this problem without difficulty be realizing that having both kittens run at the speeds given produces the same time duration as if one kitten remained at rest while the other ran toward it at 

25+12=37ms

The formula that links distance, time and speed is the definition of speed, which says

v=dt

What needs to be done here, is to change the formula so it reads t=...

To do this, multiply both sides by t and divide both sides by v. You get

t=dv

So, t=25037=6.76s