ex) you throw a baseball straght up. I returns after 3.5 sec. How fast did you throw it?
i could then use x = x(initial) + v(initial)*3.5s + 1/2(-9.8)(3.5^2) and solve for initial velocity which comes out to be 17.5m/s.
in this problem, 9.8 was negative and in some other problems, 9.8...
if not the force applied to the pedal, then it's probably the force that propels the bike forward.
*I don't remember the exact wording, but i;m sure of the info that was given.
Hi
just took my physics test today and it turns out that the 2 problems i couldn't get both happened to test my understanding of the relation between power and force. I don't have numbers but i'd like to get a better understanding of that concept so.. here's the gist of it:
There's a cyclist...
it's totally awesome that you laid out the steps, but i still managed to screw it up somehow: the answer's supposed to be 20 m/s
1) force of friction = .4(3200)(9.8) = 12,544
2) F = ma
12544 = 3200a --> a = -3.92 m/s2
3) v = v<initial>^2 + 2(-3.92)(2.8)
21.952 = v<initial> ^2
4.69...
A 1000kg toyota collides into a 2200kg Cadillac at rest. The bumpers lock, the brakes are locked, and the two cars skid forward 2.8m before stopping. The coefficient of friction btwn tires and road = .4 ... what was the speed of the toyota at impact?
I don't know how to start it off (i don't...
I got the right answer using kinematic equations (.491m) but i tried using conservation of energy and got a totally different answer:
KE initial = delta PE
1/2(0.021)(210)^2 = 1.421 (9.8) h
33.25 m = h
how am i setting up the equation wrong?
A gun is fired vertically into a 1.4 kg block of wood at rest directly above it. If the bullet has a mass of 21g and speed of 210 m/s how high will the block rise into the air after the bullet becomes embedded in it?
the total momentum in the system is 210 x .021 = 4.41,
after the collision...
right. so
mg = (mv^2)r, masses cancel, solve for v^2
v^2 = 9.8r
and E = 1/2mv^2 + mgh
mgh = 1/2m (9.8r) + m(9.8)(2r)
9.8h = 1/2 (9.8r) + (9.8)(2r)
h = 1.55 --> = height of loop
am i tackling this right so far?
a mass "m" slides without friction along a looped apparatus. If the object is to remain on the track, even at the top of the loop (whose radius is "r") from what minimum height "h" must it be released?