Answer:
F = 614913.88 N
Explanation:
We are given;
Mass of pile driver; m = 1800 kg
Height of fall of pole driver; h = 4.6 m
Depth driven into beam; d = 13.6 cm = 0.136 m
Now, from energy equations and applying to this question, we can write that;
Workdone = Change in potential energy
Formula for workdone is; W = F × d
While the average potential energy here is; W = mg(h + d)
Thus;
Fd = mg(h + d)
Where F is the average force exerted by the beam on the pile driver while in bringing it to rest.
Making F the subject, we have;
F = mg(h + d)/d
F = 1800 × 9.81 × (4.6 + 0.136)/0.136
F = 614913.88 N
The part B of the question is missing and it is;
b) What is the height between the two window ledges?
Answer:
A) 20.76 m/s
B) 161.52 m
Explanation:
A) To calculate the initial speed we use the formula from Newton's first law of motion:
v = u + at
Making u the subject gives;
u = v - at
Where;
v is the final velocity which is the speed when Jill sees the pot = 60 m/s
u is the initial velocity which is the speed when Jack sees the pot go by
t is the time between the two observed events = 4 s
a in this question is acceleration due to gravity = 9.81 m/s².
Plugging in the relevant values into the initial velocity equation gives;
u = 60 - (9.81 × 4)
u = 20.76 m/s
B) To get the height difference, we will use the formula;
(y1 - y0) = ut + ½at²
Thus, plugging in the relevant values, we have;
y1 - y0 = (20.76 × 4) + (½ × 9.81 × 4²)
(y1 - y0) = 161.52 m
