If a 60-kg woman is riding in a car traveling at 90 km/h what is her linear mome
ID: 1553009 • Letter: I
Question
If a 60-kg woman is riding in a car traveling at 90 km/h what is her linear momentum relative to: a) ground? b) the car? A 40 kg crate is at rest on a level surface. If the coefficient of static friction between the crate and surface is 0.69, what horizontal force is required to get the crate moving? What would be the acceleration if the coefficient of kinetic friction is 0.50 and the force is not changed? A student drops a ball from the top of a building. The ball takes 2.8 s to reach the ground a) What was the ball's speed just before hitting the ground? b) What is the height of the building? A hydraulic lift in a garage has two pistons: a small one of cross-section area 4.00 cm^2 and a large one of cross-section area 250 cm^2. If it is designed to raise 3500 kg car, what minimum force must be applied to the small piston? What is a rotational kinetic energy of ball moving with the constant speed 12.1 m/s? Mass of the ball is 130 g and diameter 25.0 cm. What is the mechanic energy of this ball? Each question is worth 20 points. Answer all questions with steps and units for full credit. Don't make mess. Don't forget about significant figures and rules of rounding. Give the clear answer. Return your work till Wednesday April 6th, 2017 12 pmExplanation / Answer
1)v=90 km/hr=25 m/s
(i) linear momentum relative to ground=mv=1500 kgm/s
Relative to car,speed is zero so momentum=0
(2)force required=uMg=270.48 N
If u=0.5
a =(270.48-(0.5*40*9.8))/40=1.862 m/s(2)
(3)(a) speed=9.8*2.8=27.44 m/s
(b)height=(v*v)/(2g)=38.416 m
(4) let the force is F
Pressure=F/4
Force in larger side=pressure*area=F/4 *250=3500*9.8
We got F=548.8 N
(5) Rotational energy=0.5*moment of inertia of ball*(w*w)=
Moment of inertia=0.4MR*R=8.125*10(-4)
w=v/R=96.8 rad/s
Rotational energy=3.8J
Mechanical energy=3.8+(0.5*m*v*v)=13.32 J