A 64.9 kg sprinter starts a race with an acceleration of 3.89 m/s2. She keeps this acceleration for 17 m and then maintains the
1 answer:
Answer:
Time of race = 10.18 s
Explanation:
She keeps this acceleration for 17 m and then maintains the velocity for the remainder of the 100-m dash
Time to travel 17 m can be calculated
s = ut + 0.5at²
17 = 0 x t + 0.5 x 3.89 x t²
t = 2.96 s
Velocity after 2.96 seconds
v = 3.89 x 2.96 = 11.50 m/s
Remaining distance = 100 - 17 = 83 m
Time required to cover 83 m with a speed of 11.50 m/s
Time of race = 2.96 + 7.22 = 10.18 s
You might be interested in
Answer:
a) 4.2m/s
b) 5.0m/s
Explanation:
This problem is solved using the principle of conservation of linear momentum which states that in a closed system of colliding bodies, the sum of the total momenta before collision is equal to the sum of the total momenta after collision.
The problem is also an illustration of elastic collision where there is no loss in kinetic energy.
Equation (1) is a mathematical representation of the the principle of conservation of linear momentum for two colliding bodies of masses and
whose respective velocities before collision are
and
;
where and
are their respective velocities after collision.
Given;
Note that =0 because the second mass
was at rest before the collision.
Also, since the two masses are equal, we can say that so that equation (1) is reduced as follows;
m cancels out of both sides of equation (2), and we obtain the following;
a) When , we obtain the following by equation(3)
b) As stops moving
, therefore,