A block is on a surface with µs=0.276. It takes 1.11 N to break it free from static friction. What is the mass of the block?

0.407 kg

Explanation:

Given :

Coefficient of static friction, µs = 0.276

Force, F = 1.1 N

Using the relation :

μ = F/N

N = normal reaction ; N = mg

μ = F / mg

g = acceleration due to gravity = 9.8 m/s²

0.276 = 1.1 / m * 9.8

0.276 = 1.1 / 9.8m

0.276 * 9.8m = 1.1

2.7048m = 1.1

m = 1.1 / 2.7048

m = 0.4066844

Mass = 0.407 kg

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s