91影视

Two $500g$blocks of wood are $2.0m$ apart on a frictionless table. A $10g$ bullet is fired at $400m/s$ toward the blocks. It passes all the way through the first block, then embeds itself in the second block. The speed of the first block immediately afterward is $6.0m/s$. What is the speed of the second block after the bullet stops in it?

A $100g$ granite cube slides down a $40掳$ frictionless ramp. At the bottom, just as it exits onto a horizontal table, it collides with a $200g$ steel cube at rest. How high above the table should the granite cube be released to give the steel cube a speed of $150cm/s$?

You have been asked to design a 鈥渂allistic spring system鈥� to measure the speed of bullets. A spring whose spring constant is k is suspended from the ceiling. A block of mass M hangs from the spring. A bullet of mass m is fired vertically upward into the bottom of the block and stops in the block. The spring鈥檚 maximum compression d is measured.

a. Find an expression for the bullet鈥檚 speed $v_B$ in terms of m, M, k, and d.

b. What was the speed of a data-custom-editor="chemistry" $10\mathrm{g}$bullet if the block鈥檚 mass is data-custom-editor="chemistry" $2.0\mathrm{kg}$and if the spring, with data-custom-editor="chemistry" $\mathrm{k}=50\mathrm{N}/\mathrm{m}$, was compressed by data-custom-editor="chemistry" $45\mathrm{cm}$?

In FIGURE P11.57, a block of mass m slides along a frictionless track with speed ${\mathrm{v}}_{\mathrm{m}}$. It collides with a stationary block of mass M. Find an expression for the minimum value of ${\mathrm{v}}_{\mathrm{m}}$that will allow the second block to circle the loop-the-loop without falling off if the collision is (a) perfectly inelastic or (b) perfectly elastic.

The stoplight had just changed and a 2000 kg Cadillac had entered the intersection, heading north at 3.0 m/s, when it was struck by a 1000 kg eastbound Volkswagen. The cars stuck together and slid to a halt, leaving skid marks angled 35掳 north of east. How fast was Volkswagen going just before the impact?

Ann (mass $50kg$) is standing at the left end of a $15m$long, $500kg$cart that has frictionless wheels and rolls on a frictionless track. Initially, both Ann and the cart are at rest. Suddenly, Ann starts running along with the cart at a speed of $5.0m/s$relative to the cart. How far will Ann have run relative to the ground when she reaches the right end of the cart?

FIGURE EX11.6 is an incomplete momentum bar chart for a collision that lasts $10ms$. What are the magnitude and direction of the average collision force exerted on the object?

Angie, Brad, and Carlos are discussing a physics problem in which two identical bullets are fired with equal speeds at equalmass wood and steel blocks resting on a frictionless table. One bullet bounces off the steel block while the second becomes embedded in the wood block. 鈥淎ll the masses and speeds are the same,鈥� says Angie, 鈥渟o I think the blocks will have equal speeds after the collisions.鈥� 鈥淏ut what about momentum?鈥� asks Brad. 鈥淭he bullet hitting the wood block transfers all its momentum and energy to the block, so the wood block should end up going faster than the steel block.鈥� 鈥淚 think the bounce is an important factor,鈥� replies Carlos. 鈥淭he steel block will be faster because the bullet bounces off it and goes back the other direction.鈥� Which of these three do you agree with, and why?

Force $F\left(x\right)=\left(10N\right)\sin \left(\raisebox{1ex}{$2蟺t$}\!\left/ \!\raisebox{-1ex}{$4s$}\right.\right)$is exerted on a 250 g particle during the interval$0s鈮�t鈮�2.0s$. If the particle starts from rest, what is its speed at t = 2.0 s?

A 500 g particle has velocity $v_x=-5.0m/s$at $t=-2s$. Force $F_x=4-t^2$, where t is in s, is exerted on the particle between$t=-2sandt=2s$. This force increases from 0 N at $t=-2sto4Natt=0s$ and then back to $0Natt=2s$. What is the particle鈥檚 velocity at t = 2 s?