M = r x F
r = 0
∴ M = 0
But this is clearly wrong. For some reason, the "reaction moment" must exist. Why? Where does it come from? More specifically, which force(s) produces the bending moment, and at what distance(s)? Does it come from the reaction force form the wall on the left end of the...
Homework Statement
A block floats partially submerged in a container of liquid. When the entire container is accelerated upward, which of the following happens? Assume that both the liquid and the block are incompressible.
A) The block descends down lower into the liquid.
B) The block does...
Ok I tried haruspex's method, and it seemed to work. However, I'm still a bit confused as to why it works.
I figured that the small mass element would have tensions on both sides equal to T. The two tensions must be equal since the mass element has no tangential acceleration. So now the free...
Homework Statement
A uniform thin circular rubber band of mass M and spring constant k has an original radius R. Now it is tossed into the air. Assume it remains circular when stabilized in air and rotates at angular speed ω about its center uniformly. Derive an expression for the new radius...
SHOOT! I knew there was something stupid about this problem. I thought they weren't equal since the angles between the position and velocity vectors were different... but like an idiot, I forgot to take into account that the position vector changes magnitude as well. I have no idea how I missed...
Homework Statement
(This is a problem I myself created, so it may sound a bit trivial/stupid.) A particle of mass m in the xy plane has velocity v and a radius vector r with respect to some origin. After some time Δt, the same particle has velocity v and a radius vector r' with respect to the...
Ok, the external forces acting on the car would be Weight, Normal force, and friction force. The weight is the force of Earth on the car, the normal force is a force of the surface on the car, and the friction force is another force of the surface on the car. These are the only external forces...
Homework Statement
A car attempts to accelerate up a hill at an angle θ to the horizontal. The coefficient of static friction between the tires and the hill is µ > tan θ. What is the maximum acceleration the car can achieve (in the direction upwards along the hill)? Neglect the rotational...
Yes. It does get to its initial position since the point at which the center block collides with the left most block for the second time is at the initial position. Since the center block comes to rest at the instant of collision due to conservation of momentum at the point of collision, that...
Ohhhh Since the collision is perfectly elastic, the speed of the block on the left will become zero, and the speed of the block on the left will be v. Then, after the other two blocks collide, the center block will collide again with the left block, and the speed of the center block will become...
Homework Statement
Three blocks of identical mass are placed on a frictionless table as shown. The center block is at rest, whereas the other two blocks are moving directly towards it at identical speeds v. The center block is initially closer to the left block than the right one. All motion...
I think I'm beginning to understand the part about how forces can be moved along their working lines, but I think I'd be able to understand the second situation with the force perpendicular to the working line better if I saw a diagram. I tried drawing what you said, but I just got two torques...
Homework Statement
A rotational axis is directed perpendicular to the plane of a square and is located as shown in the drawing. Two forces, F1 and F2, are applied to diagonally opposite corners, and act along the sides of the square, first as shown in part a and then as shown in part b of the...
Homework Statement
A 500-N person stands 2.5 m from a wall against which a horizontal beam is attached. The beam is 6 m long and weighs 200 N (see diagram below). A cable attached to the free end of the beam makes an angle of 45 degrees to the horizontal and is attached to the wall.
a) draw a...
Hey, I'm a beginner physics student. I'll come here mostly to ask questions related to the algebra-based AP physics 1 course I am currently taking.
(Note: IDK if I'm doing this right. After creating an account, one of the instructions in the important information just said that I needed to...