n as the block sides down the ramp? Wahat s the etfe o fition on the magnitude o
ID: 1658680 • Letter: N
Question
Explanation / Answer
for a block of mass m on incline of angle theta, coefficnet of friction k
1. acceleraTION OF BLOCK BE a
then, mgsin(theta) - k*mgcos(theta) = ma
a = gsin(theta) - k*gcos(theta)
so increasing friction decreases accelertation down the ramp
2. as acceleration has decreased due to increeasing friction
the speed with which the block leaves the ramp also decreases with increasing friction
3. As final speed has decreased due to increasing friction,
final speed = v
2*a*L = v^2
v = sqroot(2*a*L) where L is length of the ramp
now if the ramp is at height h
then , h = vsin(theta)*t + 0.5gt^2
and horizontal distance covered before hitting hte ground = R
R = vcos(theta)t
h = vsin(theta)*R/vcos(theta) + 0.5g(R^2/v^2*cos^2(theta))
0.5g*R^2/v^2*cos^2(theta) + tan(theta)*R - h = 0
so R = v^2*cos^2(theta)(-tan(theta) + sqrot(tan^2(theta) + 2gh/v^2cos^2(theta) ))/g
so when v decreases, R increases
so increasing friction decreases final speed and increases horizontal distance travelled by the block before hitting the ground
4. t = R/vcos(theta)
increasing friction increases R and decreases v so time of flight increases
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