from kinematics equation if we know that final speed is ZERO and initial speed is given that due to constant deceleration the object will stop in some distance "d" and this distance can be calculated by kinematics


here acceleration due to friction will be same at all different speed
so for 45 km/h speed the distance of stop is 15 m
while at other speed 112.5 km/h the distance will be unknown
now we will have


now divide above two equations


So it will stop in distance 93.75 m
Answer:
A. The force exerted by the sprinter must be 9.6 × 10² N.
B. The force that propels the sprinter is exerted by the blocks.
Explanation:
Hi there!
Let´s begin with part B:
The sprinter exerts a force on the blocks and, as a reaction, the blocks exert a force on the sprinter that is of equal magnitude but opposite direction (Newton´s third law). This reaction of the blocks causes the acceleration of the sprinter.
Part A
The force exerted by the blocks can be calculated using Newton´s second law:
F = m · a
Where:
F = exerted force.
m = mass of the object being accelerated.
a = acceleration of the object after applying the force on the object.
F = m · a
F = 64 kg · 15 m/s²
F = 9.6 × 10² N
Answer:
(a) Current flowing through truck battery is 180 A
(b) Time taken in calculator is 333.33 s
Explanation:
(a) Given:
The charge on the truck battery,q = 720 C
Time, t = 4.00 s
Consider I be the current flowing through truck battery.
The relation between current, charge and time is:
I = q/t
Substitute the suitable values in the above equation.

I = 180 A
(b) Given:
The charge on the calculator,q = 7.00 C
The current flowing through calculator, I = 0.3 mA = 0.3 x 10⁻³ A
Consider t be the time.
The relation between current, charge and time is:
t = q/I
Substitute the suitable values in the above equation.

I = 333.33 s
Answer:175.42m/s
Explanation:
Wavelength=0.49m
Frequency=358Hz
Velocity=frequency x wavelength
Velocity=358x0.49
Velocity=175.42m/s