Answer:
The coefficient of friction causes the force on the object to be less than its initial reading on the spring scale.
Explanation:
Since the block reads 24.5 N before the block starts to move, this is its weight. Now, when the block starts to move at a constant velocity, it experiences a frictional force which is equal to the force with which the student pulls.
Now, since the velocity is constant so, there is no acceleration and thus, the net force is zero.
Let F = force applied and f = frictional force = μN = μW where μ = coefficient of friction and N = normal force. The normal force also equals the weight of the object W.
Now, since F - f = ma and a = 0 where a = acceleration and m = mass of block,
F - f = m(0) = 0
F - f = 0
F = f
Since the force applied equals the frictional force, we have that
F = μW and F = 23.7 N and W = 24.5 N
So, 23.7 N = μ(24.5 N)
μ = 23.7 N/24.5 N
μ = 0.97
Since μ = 0.97 < 1, the coefficient of friction causes the force on the object to be less than its initial reading on the spring scale.
(a) 
According to Newton's second law, the force experienced by each balloon is given by:
F = ma
where
m = 0.021 kg is the mass
a = 1.1 m/s^2 is the acceleration
Substituting, we found:
The electrostatic force between the two balloons can be also written as
where
k is the Coulomb's constant
Q is the charge on each balloon
r = 16 m is their separation
Since we know the value of F, we can find Q, the magnitude of the charge on each balloon:
(b) 
electrons
The magnitude of the charge of one electron is
While the magnitude of the charge on one balloon is
This charge can be written as
where N is the number of electrons that are responsible for this charge. Solving for N, we find:
100/2.5 because power=energy/time
Answer:
≅3666.67 N
Explanation:
Use Newton's 2nd law, F = ma where F=force applied, m = mass of the object,
a = acceleration acquired by the object.
a= (v-u)/t where v = final velocity, u = initial velocity and t = time taken
calculate a = (30-0)/9 ≅ 3.33 m/s2
Then F = 1100×a = 3666.67 N
