Answer:
a. F = 245 Newton.
b. Workdone = 392 Joules.
c. Power = 196 Watts
Explanation:
Given the following data;
Mass = 25kg
Distance = 1.6m
Time = 2secs
a. To find the force needed to lift the mass (in N );
Force = mass * acceleration
We know that acceleration due to gravity is equal to 9.8
F = 25*9.8
F = 245N
b. To find the work done by the student (in J);
Workdone = force * distance
Workdone = 245 * 1.6
Workdone = 392 Joules.
c. To find the power exerted by the student (in W);
Power = workdone/time
Power = 392/2
Power = 196 Watts.
Answer:
D = -4/7 = - 0.57
C = 17/7 = 2.43
Explanation:
We have the following two equations:

First, we isolate C from equation (2):

using this value of C from equation (3) in equation (1):

<u>D = - 0.57</u>
Put this value in equation (3), we get:

<u>C = 2.43</u>
Change in speed = (acceleration) x (time)
4 minutes = 240 seconds
Change in speed = (40 m/s²) x (240 seconds)
Change in speed = <em>9,600 m/s</em>
What you're actually describing here is a car pulling 4 G's for 4 minutes, and ending up going 21,475 miles per hour.
The driver would definitely NOT get a speeding ticket, because nobody could catch him.
Also, his car would heat up and shoot flames from atmospheric friction.
(He could avoid this with some fancy steering, leave the atmosphere, and end up in low-Earth-orbit.)
Actually, I hope there's nobody in the car. His experience wouldn't be pretty.
Use force (thrust) equals mass times acceleration.