Physics
Grade-8
Easy
Question
A man of mass 80 kg on the top floor of a skyscraper steps into an elevator. What is the man's weight as the elevator accelerates downward at a rate of 15m/s2?
g=10m/s2
- 350 N
- 400 N
- 2000 N
- 2250 N
Hint:
Net force= m(g-a)
The correct answer is: 400 N
- When the man is elevating downwards
- Net force = mg – ma = m (g - a)
- Given that, m= 80kg, a= 15m/s2, g= 10m/s2
- Therefore, putting the values in the formula, we will get-
- = 80 x (10-15)
- = 400 N
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