Answer: option A) initially increases, then decreases.
Justification:
The increase of the rate of effective collisions among particles as the temperature increases is explained by the collision theory in virtue of the increase of the kinetic energy.
This is, as the temperature increase so the kinetic energy increase and the higher the kinetic energy the greater the number of collisions and the greater the chances that this energy overcome the activation energy (the energy needed to start the reaction).
Now, as the reaction progress the number of reactants particles naturally decrease (some of them have been converted into product) so this lower number of particles means lower concentration which means lower collisions and, thereafter, a decrease in the reaction rate.
Answer:
The tension in the string is quadrupled i.e. increased by a factor of 4.
Explanation:
The tension in the string is the centripetal force. This force is given by

m is the mass, v is the velocity and r is the radius.
It follows that
, provided m and r are constant.
When v is doubled, the new force,
, is

Hence, the tension in the string is quadrupled.
Answer:
2.5 m/s²
Explanation:
Using the formula, v = u + at ( v = Final velocity; u = Initial velocity; t = Time; a = Acceleration)
25 = 0 + 10a
a = 25/10 = 2.5 m/s²
Answer:

Explanation:
Torque,
is given by
where F is force and r is perpendicular distance
where
is the angle of inclination
Torque,
can also be found by
where I is moment of inertia and a is angular acceleration
Therefore, Fr=Ia and F=mg where m is mass and g is acceleration due to gravity
Making a the subject,
and already I is given as
hence
Taking g as 9.81,
is given as 37 and L is 1.2
Answer:
The velocity of the ball before it hits the ground is 381.2 m/s
Explanation:
Given;
time taken to reach the ground, t = 38.9 s
The height of fall is given by;
h = ¹/₂gt²
h = ¹/₂(9.8)(38.9)²
h = 7414.73 m
The velocity of the ball before it hits the ground is given as;
v² = u² + 2gh
where;
u is the initial velocity of the on the root = 0
v is the final velocity of the ball before it hits the ground
v² = 2gh
v = √2gh
v = √(2 x 9.8 x 7414.73 )
v = 381.2 m/s
Therefore, the velocity of the ball before it hits the ground is 381.2 m/s