Answer:
B.) a wheel and axle and a lever
Explanation:
P.S - The exact question is -
Given - A wheelbarrow can be used to help lift a load, such as a pile of dirt, and then push the load across a distance. A man pushes a wheelbarrow.
To find - Which simple machines make up a wheelbarrow?
A.) a pulley and an inclined plane
B.) a wheel and axle and a lever
C.) a pulley and a wheel and axle
D.) a lever and a wedge
Proof -
The correct option is - B.) a wheel and axle and a lever
Wheelbarrows are used to carry more goods from place to place by using minimal force as compared when goods are carried by hand.
With this machine, During hauling people can save time.
Answer:
0.4 m/s
Explanation:
Law of conservation of momentum tell us that the change in momentum of the hammer will be equal to the change in momentum of the astronaut
change in momentum of hammer = change in momentum of astronaut
2 kg (14 m/s - 0 m/s) = 70 kg * (v-0)
v = 0.4 m/s
Answer:
v = 88.89 [m/s]
Explanation:
To solve this problem we must use the principle of conservation of momentum which tells us that the initial momentum of a body plus the momentum added to that body will be equal to the final momentum of the body.
We must make up the following equation:

where:
F = force applied = 4000 [N]
t = time = 0.001 [s]
m = mass = 0.045 [kg]
v = velocity [m/s]
![4000*0.001=0.045*v\\v=88.89[m/s]](https://tex.z-dn.net/?f=4000%2A0.001%3D0.045%2Av%5C%5Cv%3D88.89%5Bm%2Fs%5D)
Answer:
Increase in the temperature of water would be 0.9 degree C
Explanation:
As we know by energy conservation
Change in the gravitational potential energy of the cylinder = increase in the thermal energy of the water
Here we know that the gravitational potential energy of the cylinder is given as

here we have
h = 300 m
now we can say

now if the cylinder falls from height h = 100 m
then we have

now from above two equations

