An external force moves a 3.50-kg box at a constant speed up a frictionless ramp (figure 6-46). the force acts in a direction parallel to the ramp. (a) calculate the work done on the box by this force as it is pushed up the 5.00-m ramp to a height of 3.00 m. (b) compare the value with the change in gravitational potential energy that the box undergoes as it rises to its final height. example 6-10

because growing process had stoped after 4-5 year

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg