1. A sledge loaded with bricks has a total mass of 18.8 kg and is pulled at cons

Question

1. A sledge loaded with bricks has a total mass of 18.8 kg and is pulled at constant speed by a rope inclined at 19.1° above the horizontal. The sledge moves a distance of 19.9 m on a horizontal surface. The coefficient of kinetic friction between the sledge and surface is 0.500.

(a) What is the tension in the rope?
in N
(b) How much work is done by the rope on the sledge?
in kJ
(c) What is the mechanical energy lost due to friction?

in kJ

2. Driving home from school one day you spot a ball rolling out into the street. You brake for 1.10 s, slowing your 840 kg car from 16.0 m/s to 9.50 m/s.

(a) What was the average force exerted on your car during braking?
Magnitude
kN

(b) How far did you travel while braking?
m

Explanation / Answer

Figure is missing for the 1st part !!

(2)
m = 840 Kg
t = 1.10 s
Initial Velocity , u = 16.0 m/s
Final Velocity, v = 9.5 m/s

V = u - a*t
9.5 = 16.0 - a*1.10
a = 5.91 m/s^2

(a)
Force exerted on the car during braking, F = m*a
F = 840 * 5.91 N
F = 4964.4 N

(b)
Distance travelled during the brake,
V^2 = u^2 - 2*a*S
S = (16^2 - 9.5^2)/(2*5.91)
S = 14.02 m

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