Mass m = 68 kg
center of gravity from his palms x = 0.7 m
center of gravity from his feet x ' = 1 m
forces exerted by the floor on his palms and feet are F and F ' respectively.
with respect to palms :---------------------
( F*0 ) - (W * x ) + [ F ' * (x+x') ] = 0
-mg*0.7 + F ' * 1.7 = 0 where W = weight = mg
F ' * 1.7 = mg * 0.7
F ' = mg * 0.7 / 1.7
= 68 *9.8 * ( 0.7 / 1.7 )
= 274.4 N
with respect to feet :--------------------
( F ' * 0 ) -( W* x ' ) + [F * ( x + x') ] = 0
-mg*1 + [ F * 1.7 ]= 0
F = mg / 1.7
= 392 N
Answer:
The potential energy (P.E) at the top is 392 J
The kinetic energy (K.E) at the top is 0 J
The potential energy (P.E) at the halfway point is 196 J.
The kinetic energy (K.E) at the halfway point is 196 J.
Explanation:
Given;
mass of the rock, m = 2 kg
height of the cliff, h = 20 m
speed of the rock at the halfway point, v = 14 m/s
The potential energy (P.E) and kinetic energy (K.E) when its at the top;
P.E = mgh
P.E = (2)(9.8)(20)
P.E= 392 J
K.E = ¹/₂mv²
where;
v is velocity of the rock at the top of the cliff = 0
K.E = ¹/₂(2)(0)²
K.E = 0
The potential energy (P.E) and kinetic energy (K.E) at the halfway point;
P.E = mg(¹/₂h)
P.E = (2)(9.8)(¹/₂ x 20)
P.E = 196 J
K.E = ¹/₂mv²
where;
v is velocity of the rock at the halfway point = 14 m/s
K.E = ¹/₂(2)(14)²
K.E = 196 J.
U need an insulator to prevent the shock passing through , that's why there is a plastic sheet covering the copper wires so that it can prevent the electricity passing through as plastic is an insulator and does not conduct electricity
1. A
2.B
3. True
4. False
5.B
6.B
7.B
8.True
9 true
10 true
11 true
12 C
13 D
15true
Answer:
260 km
65 km/hr
Explanation:
The displacement of an object is the distance moved by that object in a particular direction.
velocity = displacement / time, therefore,
Displacement = velocity * time.
Total displacement for the 4 HR trip = displacement for 2.5 hr + displacement for 1.5 hr
total displacement = (80 * 2.5) + (40 * 1.5)
Total displacement = 200 + 60
Total displacement = 260 Km
average velocity for the total trip = total displacement / total time taken
average velocity = 260 km/ 4 hr
average velocity = 65 km/hr
