a 75,600 n spacecraft comes in for a vertical landing. from an initial speed of 1 km/s, it comes to rest in 2 minutes with uniform acceleration.
ignoring the air resistance, what braking force must its rockets provide?
1.4 x 103n
1.4 x 10°n
1.4 x 102n
1.4 x 105n

1.4×10⁵ N

Explanation:

Find the acceleration.

Given:

v₀ = -1000 m/s

v = 0 m/s

t = 120 s

Find: a

v = at + v₀

(0 m/s) = a (120 s) + (-1000 m/s)

a = 8.33 m/s²

Find the force.

∑F = ma

F − mg = ma

F = mg + ma

F = m (g + a)

F = (75600 / 9.8) (9.8 + 8.33)

F = 1.4×10⁵ N

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.