Answer: a) 456.66 s ; b) 564.3 m
Explanation: The time spend to cover any distance a constant velocity is given by:
v= distance/time so t=distance/v
The slower student time is: t=780m/0.9 m/s= 866.66 s
For the faster students t=780 m/1,9 m/s= 410.52 s
Therefore the time difference is 866.66-410.52= 456.14 s
In order to calculate the distance that faster student should walk
to arrive 5,5 m before that slower student, we consider the follow expressions:
distance =vslower*time1
distance= vfaster*time 2
The time difference is 5.5 m that is equal to 330 s
replacing in the above expression we have
time 1= 627 s
time2 = 297 s
The distance traveled is 564,3 m
Answer:
a=
Explanation:
The net force, 
of the box is expressed as a product of acceleration and mass hence
where m is mass and a is acceleration
Making a the subject, a= 
From the attached sketch,
∑ 
where 
is frictional force and 
is horizontal angle
Substituting ∑ as in the equation where we made a the subject
a= 
Since we’re given the value of F as 240N, as 41.5N, as 
and mass m as 30kg
a= 
Answer:
No, the velocity of the grocery cart will not remain constant, but instead will increase continuously
Explanation:
No the grocery cart will not move at constant velocity over the spilled maragine because as the frictional force is changed to - 20 N, the net force will not be equal to zero
Net force on the cart when frictional force is changed to - 20 N is 40 - 20 N = 20 N
As the force is positive, it means that the force is acting in the direction of motion of the cart and will increase the velocity of the cart as the force is acting in the direction of motion
∴ The velocity of the cart will not remain constant instead it will increase
