A 300 kg boulder is dragged 8 m across level ground
with a chain that makes an angle of 37° with the
horizontal. If the applied force on the chain is 800 N
and there is a coefficient of friction of 0.20, find (a)
the work done by the applied force, (b) the force of
friction, (c) the work done by the force of friction,
(d) and the net work done by all forces.
im confused its been hours. please help!
It would help our tutors if you choose a screen name that's memorable (and pronouncable!) and stick with it. That way, a tutor will more likely connect your current question with one you have previously asked.
http://www.jiskha.com/display.cgi?id=1435292234
pulling work=800*cos37*8 Joules
force friction: (mg-800sin37)mu
friction work:(mg-800sin37)mu*8
net work. The pulling did work on friction and the movement
net work=pulling work-friction work
and the net work will equal the change of KEnergy of the boulder Notice above how pulling an an upwards angle reduces friction (have you ever moved a piano)
thanks
Sure, I can help you with that. Let's break down the problem step by step:
(a) To find the work done by the applied force, we can use the formula: Work = Force x Distance x cos(theta), where theta is the angle between the applied force and the direction of motion.
In this case, the applied force is 800 N, the distance is 8 m, and theta is 37°. Plugging these values into the formula, we get:
Work = 800 N x 8 m x cos(37°)
Now, use a calculator to find the value of cos(37°) and calculate it.
(b) To find the force of friction, we can use the formula: Force of friction = coefficient of friction x Normal force. The Normal force is the force exerted by the surface perpendicular to the object. In this case, the boulder is on level ground, so the normal force is equal to the weight of the boulder.
The weight of the boulder can be found by multiplying the mass (300 kg) by the acceleration due to gravity (9.8 m/s^2). Therefore, the weight of the boulder is 300 kg x 9.8 m/s^2.
Now, plug the coefficient of friction (0.20) and the weight of the boulder into the formula to find the force of friction.
(c) To find the work done by the force of friction, we can use the formula: Work = Force x Distance x cos(180°), where the force of friction is acting opposite to the direction of motion. The distance is still 8 m.
Plug the force of friction and the distance into the formula. Since cos(180°) is -1, the work done by the force of friction will be negative.
(d) Finally, to find the net work done by all forces, simply add the work done by the applied force and the work done by the force of friction. Make sure to consider the signs of the two works.
I hope this explanation helps you to understand how to solve the problem.