Chapter 2 - Force, Motion and Gravitation

Question 1

What is the equation for uniformly accelerated motion

Answer 1

X = Xo + Vot = 1/2gt^2

Question 2

How far will a brick starting from rest free fall for 3 seconds?

Answer 2

d = Vit + 1/2at^2
d = 1/2 (10) (9) = 45m

Question 3

A constant force of 100N pushes a 300N container across the floor. What is the force of friction acting by the floor?

Answer 3

at constant speed, forces are balance therefore 100

Question 4

Define the force of gravity

Answer 4

F = G (m1m2)/r^2

Question 5

A ball shot from a cannon vertically with Vi = 45m/s, gravity pulls back at 10m/s how long will it take to return?

Answer 5

V = Vo + at
where V = -45
-45 = 45t (-10)t
9s = t

Question 6

Acceleration due to gravity is 32ft/s what force is needed to lift a object that weighs 16lbs vertically with acceleration of 16 ft/s?

Answer 6

W = mg so m = w/g
m = 16/32 = 1/2
ma + mg
1/2 x 16 = 1/2 x 32 = 24lbs

Question 7

An object at rest is dropped, velocity on impact is 10m/s. At what height was it dropped?

Answer 7

Vf = Vo + at
10 = 0 + (10)t
t = 15 
now to get length
X = Vot + at^2
X = o + 1/2 x 10 x 1^2 = 5m

Question 8

10kg block acceleration at 2m/s up frictionless plane of 30 degrees horizontal. What is F acting parallel?

Answer 8

W = mg
W = 10 x 10 = 100
force of gravity pulling down sin 30 x 100 = 50
net force accelerating the block = ma
10 x 2 = 20
20 + 50 = 70