Answer:
73.5 m/s
Explanation:
The position of the first ball is:
y = y₀ + v₀ t + ½ at²
y = h + (0)(18) + ½ (-9.8)(18)²
y = h − 1587.6
The position of the second ball is:
y = y₀ + v₀ t + ½ at²
y = h + (-v) (18−6) + ½ (-9.8)(18−6)²
y = h − 12v − 705.6
Setting the positions equal:
h − 1587.6 = h − 12v − 705.6
-1587.6 = -12v − 705.6
1587.6 = 12v + 705.6
882 = 12v
v = 73.5
The second ball is thrown downwards with a speed of 73.5 m/s
Answer:
Explanation:
"the velocity of the block is constant, so the net force acting on the block must be zero. Thus the normal force equals the weight and the force of friction equals the applied force" The only thing which is wrongly stated here is that the normal force equals the weight. Normal force is not always equal to weight. If external force is applied at some angle with the horizon , normal force may be more or less than weight. Even in case of an object placed on an inclined plane , weight is not equal to normal force .
All other parts of the statement are correct.
Explanation:
(a) You can solve this using kinematics or energy.
Using kinematics:
a = F/m = 90 N / 4 kg = 22.5 m/s²
v₀ = 0 m/s
Δx = 5 m
Find: v
v² = v₀² + 2aΔx
v² = (0 m/s)² + 2 (22.5 m/s²) (5 m)
v = 15 m/s
Using energy:
W = ΔKE
Fd = ½ mv²
(90 N) (5 m) = ½ (4 kg) v²
v = 15 m/s
(b) ΔU = mg Δh
ΔU = (4 kg) (9.8 m/s) (12 m sin 40° − 15 m)
ΔU = -290 J
W = ΔU = -290 J
The right answer for the question that is being asked and shown above is that: "B) Earth's temperature has not changed over time." Scientists have observed that the average sunspots have increased in the last 50 years. The statement that best describes an effect of this increase in sunspots <span>Earth's temperature has not changed over time. </span>
