#1
When rocket is launched from the moon then there will be two forces on the rocket
1. Due to ejected gases the reaction force on rocket in forward direction
2. due to gravitational attraction of moon
So here we need to draw two arrow on its FBD in which first arrow is in the direction of motion of rocket which will be the reaction force on it while other arrow is opposite to its motion which is due to gravitational attraction force.
So answer would be TWO
#2
When crate is placed on the floor then in order to lift the crate upwards we always need an external force that will counter balance the normal force of crate.
Which mean if we make the normal force to be zero then crate will lift upwards and in order to make it zero we need to apply same force as that of normal force
So here the normal force is given as 150 N so we also need to apply 150 N force in order to lift it upwards
#3
If a person lift a box upwards by some force then we can say by force balance
Force applied by person + Normal force = Weight of the box

we will plug in all values in it



So we applied 150 N force on it
#4
In all cases we need to use force balance
like in case 3



so here in 3rd case tension is half of the weight
which will be the least tension in all cases
so answer is CASE 3
Answer:
a. If an object's speed is constant, then its acceleration must be zero.
FALSE
As we know that acceleration is defined as the rate of change in velocity

so we can not say anything about the acceleration when speed is given to as and no information is given about velocity
b. If an object's acceleration is zero, then its speed must be constant.
TRUE
As we know that acceleration is defined as the rate of change in velocity

Since we know that if acceleration is 0 then velocity must be constant and hence speed is also constant
c. If an object's velocity is constant, then its speed must be constant.
TRUE
Since velocity is constant then it shows that its magnitude and direction both are constant so its speed is also constant.
d. If an object's acceleration is zero, its velocity must be constant.
TRUE
As we know that acceleration is defined as the rate of change in velocity

Since we know that if acceleration is 0 then velocity must be constant
e. If an object's speed is constant, then its velocity must be constant.
FALSE
Speed is just the magnitude so we can not say about its direction and hence if speed is constant then velocity may or may not change
Answer:
0.32m/s2
Explanation:
obtained from a=wr2 where w=anular speed
r-radius
Answer:
9.93 MPa
Explanation:
Given:
- mass of the man = 68.4 kg
- Deflection dx = 5.2 cm
- thickness of plank t = 2.0 cm
- width of plank w = 13.0 cm
- Length subtended L = 2.0 m
Find:
Shear Modulus of Elasticity S :
S = shear stress / shear strain
Shear stress = F / A
Shear stress = 68.4*9.81 / 0.02*0.13
Shear stress = 258078.4615 Pa
Shear strain = dx / L
Shear Strain = 0.052 / 2
Shear Strain = 0.026
Hence,
S = 258078.4615 / 0.026
S = 9.93 MPa