Question

1. A ball is thrown upwards from the top of a building at an angle of 37degress to the horizontal with a speed of 20 m/s. components of initial velocity are x=15.9m/s y=12m/s. What are the components of velocity when it hits the ground? (x=15.9m/s but I cannot figure out y) HELP HERE PLEASE!

2. While pecking on a tree, a woodpeckers brain comes to a stop from an initial velocity of .6 m/s in a distance of 4mm a=45m/s^2 b. Calculate the stopping time (I know this one uses the pythagorean theorem, but I have not been able to solve for time.)

3. A beginning physics student needs to move a cart that has well-oiled wheels. She is about to push on it, when she rmemebrs Newtons third law, which says that it will push back on her with an equal and opposite fore. So she pushes it harder. However, obedient to Newton's third law, the cart pushes harder on her. Can she move the cart? Explain. I AM NOT SURE ABOUT THE EXPLANATION HERE

4.Two masses, 15kg and 10kg are connected by a rope (horizontally). They are pulled to the right with a force of 50N. The rope between them is taut, so they move with the same acceleration (Ignore mass of the rope and friction) Find the tension in the rope between them. NOT SURE HOW TO SOLVE THOUGH I KNOW THE ANSWER IS 20N. PLEASE HELP!

Answer 1

1) X is unchanged , Y is just negative of the first one as its coming down so -12 m/s or 12 downwards

2) Naah you don't need Pythagorean

Just use the equations of motion v=u+at

0=0.6-45*t

t=0.0133 s

3) See third law says the cart will push her back but since the cart has to move think about the forces on the cart and not her. So on the cart its her force forward and friction backwards if her force can exceed friction she will be able to move it , Yes ! Now you may think what happens to her cart pushes her back which is fine but she may have had shoes with high grip so friction will stop her from sliding back. But since we are considering cart we will not talk of her unless asked.

4) Lets take them together 50=25 a

a= 2 m/s2

now use consider 10 kg

10 kg is pulled because of tension so T=ma= 10*2= 20 N