Physics 1 Final, Questions & Answers

Physics 1 Final, Questions & Answers 4.00 × 105 J of work are done on a 1167 kg car while it accelerates from 10.0 m/s to some final 77) velocity. Find this final velocity. C) 28.0 m/s - ANSWER: wtotal= [1/2 m*vf²] - [1/2 m*vi²] x= vf 57) A 22 kg box must be slid across the floor. If the coefficient of static friction between the box and floor is 0.37, what is the minimum force needed to start the box moving from rest? A) 80 N - ANSWER: F- µ • mg = 0 F=22 µ= 0.37 F= m•g•µ =80 58) A force of 30 N stretches a spring 0.73 m from equilibrium. What is the value of the spring 58) constant? A) 41 N/m - ANSWER: Fspring = -Kx F/x =K 30/0.73 = K = 41 87 J of work are needed to stretch a spring from 1.4 m to 2.9 m from equilibrium. What is the value 76) of the spring constant? C) 39 N/m - ANSWER: w=f•d , F= w/d F= Kx , K= F/x F = 87J / 1.5 = 58N K= 58N / 1.5 = 39 N/m A 0.140 kg baseball is thrown with a velocity of 28.9 m/s. It is struck with an average force of 84) 5000.0 N, which results in a velocity of 37.0 m/s in the opposite direction. How long were the bat and ball in contact? B) 1.85 × 10-3 s - ANSWER: Impulse is change in momentum I = m (vf-vi) T = m ( - vf - vi ) / F = 1.85 X 10^-3 (in miliseconds) A 0.16 kg block on a horizontal frictionless surface is attached to a spring whose force constant is 16) 360 N/m. The block is pulled from its equilibrium position at x = 0 m to a displacement x = +0.080 m and is released from rest. The block then executes simple harmonic motion along the x-axis (horizontal). When the displacement is x = -0.037 m, the acceleration of the block is closest to: A) 85 m/s2 - ANSWER: ma= -kx so, a= -kx/m m=0.16 kg, x= -0.037, k= 360 [ -360 (-0.037) ] / 0.16kg = 84 m/s^2 A 0.39 kg block on a horizontal frictionless surface is attached to a spring whose force constant is 15) 570 N/m. The block is pulled from its equilibri