Answer:
180 W
Explanation:
The work done by the man against gravity is equal to its gain in gravitational potential energy:

where
(mg) = 720 N is the weight of the man
is the change in height
Substituting,

The power he must deliver is given by

where
W = 3600 J
t = 20 s is the time taken
Substituting,

210J
PE is mgh in this context.
Negative
Because the car is moving up and the bug is moving down. but it also depends on the weather so choice between one of those two I think is Negative but I may be wrong.
When talking about orbits, it would have to be a mixture of both A. and B. since Newton's first law, gravity plays a huge part in an orbit. However, the universal gravitation law also tells us the relationship between two massive objects in orbit. But to choose only one, it would have to be B. Newton's first law
Answer:
9.96x10^-20 kg-m/s
Explanation:
Momentum p is the product of mass and velocity, i.e
P = mv
Alpha particles, like helium nuclei, have a net spin of zero. Due to the mechanism of their production in standard alpha radioactive decay, alpha particles generally have a kinetic energy of about 5 MeV, and a velocity in the vicinity of 5% the speed of light.
From this we calculate the speed as
v = 5% 0f 3x10^8 m/s (speed of light)
v = 1.5x10^7 m/s
The mass of an alpha particle is approximately 6.64×10−27 kg
Therefore,
P = 1.5x10^7 x 6.64×10^−27
P = 9.96x10^-20 kg-m/s