Friction acts on the ball and causes it to stop
Answer:
<em>Answer: B. 49 N</em>
Explanation:
<u>Friction Force
</u>
When an object is at rest on a rough surface, it encounters a friction force that opposes motion.
The friction force when an object is moving on a horizontal surface is calculated by:
Where 
is the coefficient of static friction and N is the normal force.
If no forces other then the weight and the normal are acting upon the y-direction, then the weight and the normal are equal in magnitude:
N = W = m.g
Thus, the friction force is:
We are given the coefficient of static friction 
and the mass of the object m=10 Kg. The minimum force needed to make it start moving is the maximum friction force:
Fr=0.5*10*9.8
Fr = 49 N
Answer: B. 49 N
Answer:
630.75 j
Explanation:
from the question we have the following
total mass (m) = 54.5 kg
initial speed (Vi) = 1.4 m/s
final speed (Vf) = 6.6 m/s
frictional force (FF) = 41 N
height of slope (h) = 2.1 m
length of slope (d) = 12.4 m
acceleration due to gravity (g) = 9.8 m/s^2
work done (wd) = ?
- we can calculate the work done by the boy in pushing the chair using the law of law of conservation of energy
wd + mgh = (0.5 mVf^2) - (0.5 mVi^2) + (FF x d)
wd = (0.5 mVf^2) - (0.5 mVi^2) + (FF x d) - (mgh)
where wd = work done
m = mass
h = height
g = acceleration due to gravity
FF = frictional force
d = distance
Vf and Vi = final and initial velocity
wd = (0.5 x 54.5 x 6.9^2) - (0.5 x 54.5 x 1.4^2) + (41 x 12.4) - (54.5 X 9.8 X 2.1)
wd = 630.75 j
