Question

2. A crate is pushed horizontally at an angle of 20° across a rough surface as shown. The mass of the crate is 55 kg and the coefficient of kinetic friction M = 0.35. a) What applied force is required to keep the box moving at a constant acceleration of 3m/s2 ? b) What applied force is needed to keep the box moving at a constant speed, that is, no acceleration? (2 pts.) 3. A 60-kg skier starts from rest at the top of a ski jump, point A above, and travels down the ramp to point B. If friction and air resistance can be neglected, a) Determine her speed VB when she reaches the horizontal end of the ramp at B and her kinetic energy. (3 pts.)

Answer 1

PAGE NO DATE given O=20 m = 55 kg Mp = 0.35 from free badly diagram of Crate @ AN Proszo fk op mg + P sinao Forces are acting on Crate. 1-weight = mg 2. N=nonmal force 3. P= Pushing force fx kinetic fiction. Netforce 552= Plos2o - for 550 - 10.94) PC MAN 55 a : 0.94 P - C0.35)[mg + P sin 20) 55 a = 0.942 – (0.35x55x9.8) - (0-35 x P x 0.342)

ssa: 0.94 P - 188.65 PAGE NO. -0,1197 DPE - 56132. = 0.94 P-011197 p - 188.65 353.65 = 0.8203 P. (P = 431N] = Pushing force. b if it has constant speed means a=0 in 0=0.94P - 188.65 -0.1197 P. o=0.8203P - 188.65 P: 229 N P=230N Answer